Merge pull request #25 from josephktcheung/API

Api
ADDED conversation controller and views for index and show.
ADDED conversation controller and views for index and show.
REMOVED uncompressed public file.
Merge pull request #26 from annieccheung/conversation_json

Conversation json
ADDED messages to conversation show api.
Merge pull request #27 from annieccheung/conversation_json

ADDED messages to conversation show api.
UPDATED apprenticeship/show view
ADDED apprenticeship/new json rabl and test cases