Initial Pry integration.
Fix interactor DSL spec.
Try to load ~/.guardrc first.
Fix wrong param name.
Change pause prompt.
Hook instead of RC_FILES; Increased verbosity.

Pry::RC_FILES went away recently, in this commit:
  https://github.com/pry/pry/commit/d830ebbacc6ebaf60261855ef6011bd6b9d47d8d

The hooks should work both in 0.9.10 and HEAD pry.

Also, gave the user a hint about ~/.guardrc, because it changes the
interactor experience quite a bit with/without one.
Merge branch 'master' into interactor/pry
Remove global Pry hook after each spec.
Add tmux notifier
Fix notifier spec to stub out the tmux add_notifier call
Allow default colors to be overwritten in tmux notifier
Change tmux status bar to status-left-bg
Move the interactor shorthand alias examples to the README.

 We should try to avoid to much noise from Guard about a specific
 preferred setup.

 Thanks @rking for https://gist.github.com/da7f4b2f8465a3d75cd4
Add missing specs.
Ensure consistent code style for all notifiers.
Reorganize notifier list.
Update CHANGELOG.
Fix textual changes on the specs.
Update Guard plugin count :P
Add OS specific installation instructions. (Fixes #330)