use Guard::Compat
update to RSpec 3.1
do not require gems in Gemfile
use halt_on_fail in Guardfile
add hound-tools
add RuboCop to Rakefile
RuboCop setup + fix offenses
fix gem deps for Travis
Merge pull request #124 from guard/use_guard_compat

use Guard::Compat and update to RSpec 3.1