FC014: Don't error without block attr, refs #139.
add feature: specify rule tags in any cookbook's .foodcritic file
Issue 143 - Provide a search rubygems option to load custom rules from a gem.

- Added search for ruby gems option -G (or --search-gems)
- If option is given then search gems for foodcritic/rules/**/*.rb and add these to the
  list of files loaded by the RuleDsl.
Merge remote-tracking branch 'bpaquet/master'
Update regression test for definitions, refs #142.
Issue 143 - Only use latest gems when searching for rules files.

- Also added some specs for rule file loading.
Fix cucumber test, add presence check for .foodcritic file
Include docs and LICENSE in the gem
Include tests in gem too
Merge remote-tracking branch 'rally/issue-143'
Merge remote-tracking branch 'stefanor/include-docs-in-gem'
fix bug that guaranteed we would not see tags
Merge remote-tracking branch 'gapinc/rule-tag-files'
Replace rak hack with our own context-output plugin
Merge remote-tracking branch 'stefanor/rak-free'
Manpage in markdown (ronn)
Build & install manpage
Specify a rdiscount version that'll work on ruby 1.9.2
Gitignore ronn build output
Refactor failure indication onto Warning instead of Review

* To make it easier to perform different operations against
  failures vs. warnings, move the failure status onto individual
  FoodCritic::Warning objects

* Added #failures method to Review which will return a list of
  warnings that are failed

* Refactored gherkin tag matching into Rule