Respect ReturnUrl through login process / Update a bunch of jabbr infrastructure

ReturnUrl should be maintained a bunch more than it is at current.  This change makes it so that when a user enters an incorrect password, returnUrl is kept (fixes #737).  The hash value is also kept across requests (anchors and forms from the login page) thanks to a couple of lines of javascript (fixes #652).

For social providers, we had to update to the latest WorldDomination authentication (now SimpleAuthentication).  This required some other updates, so everything's a pretty recent version now.  In doing this, I updated the login page to use fontawesome, and rejigged the buttons slightly.
![jabbr-login-buttons](https://f.cloud.github.com/assets/1271535/882729/3d5f3730-f969-11e2-87c5-0a71dcb4531c.png)