Added gem dependencies
Updated database schema with restrictive actions
Integrated LinkedIn API access

* Gets the 'access_token' from LinkedIn and inserts the token along with user email, register/expire timestamps
* Added database models for accounts, keys
* Enforced rule such that, successive registration of the same user will update the token in the database

* NOTE: Currently there is a bug in the system, where after the first successful login, successive attempts at registration will result in an invalid token, this bug does not exist in the test environment (http://github.com/jnwu/prototype-test)
Embedded link for triggering LinkedIn login

* Currently the link is commented, as the system bug (as commented in the previous commit) is being looked into
Merge branch 'master' of github.com:ChristopherTulip/prototype