Gossyper may react to gossyp

* Change gossyp_spec to use shoulda-matchers
* Extract models, routes, and helpers to own files
* Posting to create gossyp requires login
* Rename responses to reactions
* Gossyper may not react without a body
Merge pull request #8 from tiger-swallowtails-2013/gossyper_may_respond_to_discussion_squashed

Gossyper may react to gossyp