Exit gracefully on unsupported Rubies

Instead of throwing an exception RuboCop now displays
a message when ran on an unsupported Ruby. This fixes #113.
Add new cop WordArray
Update ST2 plugin link
New rule: use spaces inside hash literal braces, or don't.

Which style to use is configurable. Default is with spaces.
Merge pull request #114 from jonas054/hash_literal_spaces

New rule: use spaces inside hash literal braces, or don't.
Add new cop LineContinuation
Minor changelog improvements
Add new cop SymbolArray

It's disabled by default since many people (like us) might still be
targeting both Ruby 1.9 and 2.0.
Fixed pluralization for 0 files detected
Fixed Rakefile
Added support for includes and excludes