Add syntax checker for YAML using JS-YAML
Merge branch 'master' into yasuyk-js-yaml

* master: (128 commits)
  Update credits and changelog
  Fix Handlebars URL
  Boldly add myself to the credits
  Remove duplicated credits
  Demote Rubocop convention messages to info level
  Update credits
  Fix test cases
  Fix error sorting stability
  Restore proper order of error tokens
  Refactor ruby test cases
  Remove ruby and ruby-jruby checkers [#250]
  Update changelog
  Install Ruby headers to build native extensions
  Fix test case names
  Add key binding to set the executable
  Warn about non-interactive use of -set-checker-executable
  Add executable variable to syntax checker docs
  Add command to select the syntax checker executable
  Add executable variables for syntax checkers [#143]
  Remove superfluous test case
  ...

Conflicts:
	puppet/modules/flycheck/manifests/checkers.pp
	test/builtin-checkers-test.el
Update credits and changelog
[Fix #253] Merge branch 'yasuyk-js-yaml'

* yasuyk-js-yaml:
  Update credits and changelog
  Add syntax checker for YAML using JS-YAML
Allow failures on Emacs snapshot

Package installations from MELPA fail on Emacs snapshot, see
https://github.com/milkypostman/melpa/issues/1193