Add realtime dependency for json
Rubinius is set as optional

- build bug in travisci https://github.com/travis-ci/travis-ci/issues/2821

Conflicts:
	.travis.yml
Merge pull request #51 from apiaryio/abtris/fix-json-dependency

Add realtime dependency for json
Add redsnow to dependecies
Move validate_apib_file function into common.rb
Add test for validate_apib_file
Add test for validate_blueprint via RedSnow
Using SnowCrash to validate API Blueprint before sending request to Apiary
Update dependency
Remove travis cache for bundle
Rubinius is set as optional

- build bug in travis-ci https://github.com/travis-ci/travis-ci/issues/2821