Add syntax checker for JavaScript using ESLint

For information about ESLint, See https://github.com/nzakas/eslint.
Sort dependencies alphabetically
Fix indentation
Fix Rubocop test cases

Recent Rubcop releases removed the SymbolName cop entirely
Improve docs of flycheck-eslint-rulesdir
Update changelog
[Fix #291] Merge branch 'yasuyk-eslint'

* yasuyk-eslint:
  Update changelog
  Improve docs of flycheck-eslint-rulesdir
  Add syntax checker for JavaScript using ESLint
Use f.el helpers where possible
Require a file name for go build and go test
Add syntax checker for eRuby using erubis command
Test eruby in Web Mode, too
Update credits and changelog
[Fix #285] Merge branch 'yasuyk-eruby-erubis'

* yasuyk-eruby-erubis:
  Update credits and changelog
  Test eruby in Web Mode, too
  Add syntax checker for eRuby using erubis command
Restore alphabetical ordering of extensions
Add flycheck-mercury to the list of extensions

See https://github.com/flycheck/flycheck-mercury
Fix Python test cases for Pylint 1.1
Fix error list test cases
Release 0.16
Bump version in master