fix confusion in browserid-network.  when auth status is non-boolean it means it requires a fetch, otherwise we expect it to represent authentication status of the session

issue #329 - fold am_authed call into session_context to minimize network requests.  update browserid-network.js abstraction to shield higher level code from these changes (higher level code doesn't know/care whether a network function maps onto zero, one, or more wsapi calls)

server side changes for issue #329 - /csrf call is now /session_context and returns current server time - to be used to allow clients with broken clocks to generate valid assertions

ensure users must authenticate every week (issue #309).  Also, move all magic numbers out of implementation and into the configuration abstraction.

fix issue where hash changes during dialog interaction would break things.  extract relay frame id from hash at load time.  closes #295

remove migrate_to_certs.sql from dev, it's not relevant anymore (its an ad-hoc step that's riding train-2011.09.22)

fix issue where hash changes during dialog interaction would break things.  extract relay frame id from hash at load time.  closes #295

improve documentation of changes to window opening to deal with firefox bugs and code loading race conditions

use onready instead of polling to fix race condition related to window vs relay frame readiness, and fix problems in FFX with re-attaching iframes of the same name, by creating relay frames with unique names every time.

issue #287 & issue #286

Every time we create a relay frame, give it a new name.

issue #287.