refactored label and pull-request classes
fixed documentation and tests
Merge pull request #22 from sportngin/op-test

Added ability to add deployable label
Merge branch 'master' of github.com:sportngin/octopolo into risk-labels

Conflicts:
	lib/octopolo/github/label.rb
	spec/octopolo/github/label_spec.rb
updated pull_request script to reflect change in pull_request model