[Fix #275] Remove hdevtools syntax checker

hdevtools is failing to build on the testing environment, and seems
poorly maintained.
Add Chef cookbooks syntax checker using Foodcritic
Put chef-foodcritic after c/c++-cppcheck
Fix chef-foodcritic checker

- add a predicate
- remove next-checker
Update a test case of chef-foodcritic
Add syntax checker for AsciiDoc using AsciiDoc compiler
Fix predicate of chef-foodcritic syntax checker

See https://github.com/flycheck/flycheck/pull/255/files#r8033685
Move xml header packages into Ruby class

That's conceptually the right place, and makes sure that these are
installed before the foodcritic Gem on Vagrant
Update credits
[Fix #255] Merge branch 'yasuyk-chef-foodcritic'

* yasuyk-chef-foodcritic:
  Update credits
  Move xml header packages into Ruby class
  Fix predicate of chef-foodcritic syntax checker
  Update a test case of chef-foodcritic
  Fix chef-foodcritic checker
  Put chef-foodcritic after c/c++-cppcheck
  Add Chef cookbooks syntax checker using Foodcritic
Improve dependencies of Gem provisioning

Don't make the choice based on environment information, but instead just
check whether the class is defined.
Fix name of libxslt header package
Update Ruby tests

The latest ruby-lint fixes the column offsets, so we need to adjust the
columns in our test cases.
Add test for syntax errors from ruby-lint
Do not require libraries up front

Instead, use explicit autoloads to load them on demand.  This speeds up
initial load, and thus the execution of individual tests.
Use a common naming pattern for all tests

Prefix a test with the name of the function or variable being tested, or
`flycheck` if no specific function or variable is being tested,
separated from the test name by a slash.
Require old cl for mocker.el
Add AsciiDoc to README
Merge branch 'master' into yasuyk-asciidoc

* master:
  Require old cl for mocker.el
  Use a common naming pattern for all tests
  Do not require libraries up front
  Add test for syntax errors from ruby-lint
  Update Ruby tests
  Fix name of libxslt header package
  Improve dependencies of Gem provisioning
  Update credits
  Move xml header packages into Ruby class
  Fix predicate of chef-foodcritic syntax checker
  Update a test case of chef-foodcritic
  Fix chef-foodcritic checker
  Put chef-foodcritic after c/c++-cppcheck
  Add Chef cookbooks syntax checker using Foodcritic

Conflicts:
	test/builtin-checkers-test.el
Update changelog and credits