Look for plugins under the source directory

When generating the site, Jekyll will now look for plugins under the
source directory by default. The plugin location can still be changed in
_config.yml
Bump kramdown, rake, shoulda, cucumber, redcarpet
Add test/unit
Merge remote-tracking branch 'upstream/master' into issue-653
Look for plugins under the source directory by default
Add TomDoc
Dont test kramdown

It should have it's own tests for that
Merge branch 'master' into issue-653
Ensures that categories are Strings before escaping. Fixes #759.
Added test for all-String categories.
Update command classes moving into a module
Strip extra newlines
Update converter classes moving into a module
Update pagination classes moving into a module
Update tag classes moving into a module
Remove new lines between module and class
Added simplecov-gem-adapter dev dependency.
Only running simplecov if RUBY_VERSION is 1.9 or greater, and COVERAGE env is set to 'true'
Merge pull request #771 from mojombo/fix-coverage

Fix SimpleCov Execution
Updated history to reflect merge of #771.