fix(cli): re-enable parallel scripts

PR #29 broke the following case:

```
p-s -p lint,test
```

This commit fixes it by getting the scripts from the args first and
seeing if there are any scripts available to run. If not, then we show
the help message.

.travis.yml

@@ -15,7 +15,7 @@ before_install:
 before_script:
   - npm prune
 script:
-  - npm start validate
+  - npm run localstart validate
 after_success:
   - 'curl -Lo travis_after_all.py https://git.io/travis_after_all'
   - python travis_after_all.py

package-scripts.js

@@ -45,7 +45,7 @@ module.exports = {
     },
     validate: {
       description: 'This runs several scripts to make sure things look good before committing or on clean install',
-      script: `p-s -p ${validate.join(',')} && p-s check-coverage`,
+      script: `dist/bin/p-s.js -p ${validate.join(',')} && p-s check-coverage`,
     },
     addContributor: {
       description: 'When new people contribute to the project, run this',

src/bin-utils.js

@@ -43,15 +43,15 @@ export {getScriptsAndArgs, help, getModuleRequirePath, preloadModule, loadConfig
 /****** implementations ******/
 
 function getScriptsAndArgs(program) {
-  let scripts, args, parallel
-  if (isEmpty(program.parallel)) {
-    scripts = program.args[0].split(',')
-    args = getArgs(program.args.slice(1), program.rawArgs, scripts)
-    parallel = false
-  } else {
+  let scripts = []
+  let args = ''
+  const parallel = !isEmpty(program.parallel)
+  if (parallel) {
     scripts = program.parallel.split(',')
     args = getArgs(program.args, program.rawArgs, scripts)
-    parallel = true
+  } else if (!isEmpty(program.args)) {
+    scripts = program.args[0].split(',')
+    args = getArgs(program.args.slice(1), program.rawArgs, scripts)
   }
   return {scripts, args, parallel}
 }

src/bin-utils.test.js

@@ -32,6 +32,15 @@ test('getScriptsAndArgs: passes args to scripts', t => {
   t.is(args, '--watch --verbose')
 })
 
+test('getScriptsAndArgs: returns empty scripts and args if not parallel and no args', t => {
+  const {args, scripts} = getScriptsAndArgs({
+    args: [],
+    rawArgs: ['node', 'p-s'],
+  })
+  t.is(scripts.length, 0)
+  t.is(args, '')
+})
+
 test('preloadModule: resolves a relative path', t => {
   const relativePath = '../test/fixtures/my-module'
   const val = preloadModule(relativePath)

src/bin/p-s.js

@@ -21,14 +21,14 @@ program
   .on('--help', onHelp)
   .parse(process.argv)
 
-if (program.args.length < 1) {
+const scriptsAndArgs = getScriptsAndArgs(program)
+if (scriptsAndArgs.scripts.length < 1) {
   program.outputHelp()
 } else {
   loadAndRun()
 }
 
 function loadAndRun() {
-  const scriptsAndArgs = getScriptsAndArgs(program)
   const psConfig = getPSConfig()
 
   runPackageScript({