update: Improve makefile commands and fix lint

Improved the makefile for making the development more easy and fixed
the issue returned by linter.
Added the contributing file.

.travis.yml

@@ -11,18 +11,15 @@ services:
   - redis-server
   - mongodb
 
-env:
-  - DEP_VERSION="0.4.1"
-
 before_install:
-  - curl -L -s https://github.com/golang/dep/releases/download/v${DEP_VERSION}/dep-linux-amd64 -o $GOPATH/bin/dep
-  - chmod +x $GOPATH/bin/dep
   - go get github.com/axw/gocov/gocov
   - go get github.com/mattn/goveralls
   - if ! go get github.com/golang/tools/cmd/cover; then go get golang.org/x/tools/cmd/cover; fi
 
 install:
-  - dep ensure
+  - make depend
+  - make configure
 
 script:
-    - $HOME/gopath/bin/goveralls -service=travis-ci
+  - make lint
+  - $HOME/gopath/bin/goveralls -service=travis-ci

CONTRIBUTING.md

@@ -0,0 +1,66 @@
+# Contributing
+
+By participating to this project, you agree to abide our [code of conduct](/CODE_OF_CONDUCT.md).
+
+## Setup your machine
+
+`cachego` is written in [Go](https://golang.org/).
+
+Prerequisites:
+
+* `make`
+* [Go 1.8+](https://golang.org/doc/install)
+
+Clone `cachego` from source into `$GOPATH`:
+
+```sh
+$ mkdir -p $GOPATH/src/github.com/fabiorphp
+$ cd $_
+$ git clone [email protected]:fabiorphp/cachego.git
+$ cd cachego
+```
+
+Install the build and lint dependencies:
+```console
+$ make depend
+```
+
+A good way of making sure everything is all right is running the test suite:
+```console
+$ make test
+```
+
+## Formatting the code
+Format the code running:
+```console
+$ make fmt
+```
+
+## Create a commit
+
+Commit messages should be well formatted.
+Start your commit message with the type. Choose one of the following:
+`feat`, `fix`, `docs`, `style`, `refactor`, `perf`, `test`, `chore`, `revert`, `add`, `remove`, `move`, `bump`, `update`, `release`
+
+After a colon, you should give the message a title, starting with uppercase and ending without a dot.
+Keep the width of the text at 72 chars.
+The title must be followed with a newline, then a more detailed description.
+
+Please reference any GitHub issues on the last line of the commit message (e.g. `See #123`, `Closes #123`, `Fixes #123`).
+
+An example:
+
+```
+docs: Add example for --release-notes flag
+
+I added an example to the docs of the `--release-notes` flag to make
+the usage more clear.  The example is an realistic use case and might
+help others to generate their own changelog.
+
+See #284
+```
+
+## Submit a pull request
+
+Push your branch to your `cachego` fork and open a pull request against the
+master branch.

Makefile

@@ -1,19 +1,49 @@
-.PHONY: clean configure test test-coverage
-
 .DEFAULT_GOAL := test
 
+# Clean up
 clean:
-	@rm -fR vendor/ cover.*
-	@docker-compose stop
-	@docker-compose rm -f
+	rm -fR ./vendor/ ./cover.*
+.PHONY: clean
 
+# Download dependencies
 configure:
-	@dep ensure -v
-	@docker-compose up -d
+	dep ensure -v
+.PHONY: configure
 
-test:
-	@go test -v .
+# Run tests and generates html coverage file
+cover: test
+	go tool cover -html=./cover.out -o ./cover.html
+.PHONY: cover
+
+# Download dependencies
+depend:
+	go get -u gopkg.in/alecthomas/gometalinter.v2
+	gometalinter.v2 --install
+	go get -u github.com/golang/dep/...
+.PHONY: depend
+
+# Up the docker container for testing
+docker:
+	docker-compose up -d
+.PHONY: docker
 
-test-coverage:
-	@go test -coverprofile=cover.out -v .
-	@go tool cover -html=cover.out -o cover.html
+# Format all go files
+fmt:
+	gofmt -s -w -l $(shell go list -f {{.Dir}} ./... | grep -v /vendor/)
+.PHONY: fmt
+
+# Run linters
+lint:
+	gometalinter.v2 \
+		--vendor \
+		--disable-all \
+		--enable=golint \
+		--enable=gofmt \
+		--enable=misspell \
+		--enable=vet ./...
+.PHONY: lint
+
+# Run tests
+test:
+	go test -v -race -coverprofile=./cover.out $(shell go list ./... | grep -v /vendor/)
+.PHONY: test

README.md

@@ -208,19 +208,31 @@ Read the full documentation at [https://godoc.org/github.com/fabiorphp/cachego](
 - Install [docker](https://docs.docker.com/install/) and [docker-compose](https://docs.docker.com/compose/install/)
 - Install [go dep](https://github.com/golang/dep)
 
-### Run tests
+### Makefile
 ```sh
-// tests
-$ make test
-
-// test with coverage
-$ make test-coverage
-
-// clean-up
+// Clean up
 $ make clean
 
-// configure (download dependencies and run docker containers)
+// Creates folders and download dependencies
 $ make configure
+
+//Run tests and generates html coverage file
+make cover
+
+// Download project dependencies
+make depend
+
+// Up the docker containers for testing
+make docker
+
+// Format all go files
+make fmt
+
+//Run linters
+make lint
+
+// Run tests
+make test
 ```
 
 ## License

sqlite3_test.go

@@ -20,8 +20,8 @@ type Sqlite3TestSuite struct {
 }
 
 var (
-	cacheTable string = "cache"
-	dbPath     string = "./cache.db"
+	cacheTable = "cache"
+	dbPath     = "./cache.db"
 )
 
 func (s *Sqlite3TestSuite) SetupTest() {