let FirefoxOS sessions last for 10 years
Fix the failing FirefoxOS session duration tests.

The wsapi library has an internal context. If a context is passed to the wsapi library, the internal context is not updated. When fetching cookies for FirefoxOS tests, make sure to fetch them from the correct context.
Start to add "supress_ask_if_users_computer" for the authentication functions.
update the front end to handle forever sessions.

* Only from calls to user.authenticate and user.authenticateWithAssertion.
Merge branch 'b2g-session-duration' of github.com:mozilla/browserid into b2g-session-duration
consolidated duration_ms and is_firefos_duration in one object