Feature server subscription

## Server
- Created Subscription model
- Added timestamps to all models and presave hook to update them
- Subscribe/Unsubscribe routes
- Created outline for update subscriptions job
- Added cors to allow for server to accept requests from client

## Client
- Added config to whitelist dev server url
- Added dev server url to `$rootScope`
- Created LoginService (should rename to AuthService?)
- Created ApiKeyService for storing and retrieving api credentials
- Fleshed out login function in loginCtrl (still requires redirect to some auth'd area)