Browspr Authentication support.

When a veyron web app asks for authentication, it sends an 'auth'
message to the extension, which creates and associates an account on
WSPR.

Previously, the extension was communicating with WSPR over HTTP.

Now, the extension must communicate with Browspr over postMessage.

This CL:
* Sets up a channel for browspr RPCs.
* Uses channel RPCs for "start", "cleanup", "createAccount" and
  "associateAccount" messages.
* Moves the account test into browspr, and uses channel RPCs rather than
  HTTP.
* Adds a "RootAccount" to the account manager, and methods for the
  extension to ask if the root account has been set.
* Adds principal.TrustIdentdBlessingRoot, which tells browspr to trust
  the public key and blessing names from the identdurl and add them to
  its trusted roots.  This must be done before making a veyron rpc to
  the identity server.
* Moves fileSerializer into its own file.

MultiPart: 2/2

Change-Id: I1e166ce1fc5b75f0b7b011c0ee3388ac42456c3a
12 files changed
tree: 55b0a212a62896544aa974d1252b04b201b7978f
  1. services/