v4.0.0

Build

• ember-cli-update
• remove fastboot and all related items
• deps: [security] bump jquery from 3.3.1 to 3.4.0 (#246)
• deps: [security] bump lodash.defaultsdeep from 4.6.0 to 4.6.1 (#270)
• deps: update ember-decorators to 6.0.0
• deps-dev: bump eslint-plugin-ember from 6.2.0 to 6.3.0 (#224)
• deps-dev: bump ember-angle-bracket-invocation-polyfill from 1.2.5 to 1.3.1 (#249)
• deps-dev: bump ember-cli-template-lint from 1.0.0-beta.2 to 1.0.0-beta.3 (#241)
• deps-dev: remove ember-exam
• deps-dev: bump ember-source from 3.8.0 to 3.9.1 (#236)
• deps-dev: bump ember-cli-addon-docs from 0.6.7 to 0.6.10 (#238)
• deps-dev: bump ember-cli-addon-docs from 0.6.6 to 0.6.7 (#222)
• package.json: update ember-addon.versionCompatibility min version

CI

• travis: yarn upgrade ember-cli-template-lint (#276)

Docs

• package.json: update versionCompatibility to be at least v2.18.x
• readme: more conventional addon README format
• readme: update release docs with latest info

Refactors

• remove old base class, modernize, remove outdated deps (#277)
• package.json: remove lodash.defaultto

Reverts

• Revert "refactor(package.json): remove lodash.defaultto"
• refactor(package.json): remove lodash.defaultto