chore(package): downgrade mocha to version 2.5.3
chore(package): downgrade mocha to version 2.5.3

Error on Travis:

    npm ERR! peerinvalid The package mocha@3.0.0-1 does not satisfy its siblings' peerDependencies requirements!
    npm ERR! peerinvalid Peer karma-mocha@1.1.1 wants mocha@*

ybiquitous/backbone.deepmodel,ybiquitous/backbone.deepmodel