Bug 1015085 - Loop server - Implement User Calls Other User by ID flow. ...

...r=alexis
Semi-related; GitHub search for [`getTime()`](https://github.com/mozilla-services/loop-server/search?q=getTime%28%29&type=Code) currently returns 4 results:

1. [/loop/headers.js:11](https://github.com/mozilla-services/loop-server/blob/092bdc4cc46c0dde7dbcbd80b0fda1ef6a307de0/loop/headers.js#L11)
2. [/loop/tokbox.js:46](https://github.com/mozilla-services/loop-server/blob/ed2d0d1a9f88fcc06aa2a0c38ed07958dc59448a/loop/tokbox.js#L46)
3. [/loop/tokenlib.js:131](https://github.com/mozilla-services/loop-server/blob/092bdc4cc46c0dde7dbcbd80b0fda1ef6a307de0/loop/tokenlib.js#L131)
4. [/loop/index.js:503](https://github.com/mozilla-services/loop-server/blob/9f04ee4fba1ea4c1b8dc6bf31d263787c2f7e387/loop/index.js#L503)