Login dialog changes

Themed the login dialog box to match JCU colours and made the login
option of AAF the more obvious choice for users.

Note these changes make the current login form look good but may break
if additional authentication plugins are added to our installation at a
later date.

login.vm:
Added javascript to toggle some styles on sections of the login form.

login-form.vm:
Added some id and class elements to different elements to give anchor
points for the javascript in login.vm
Change legend text for the local login form.

local.css:
Color and style changes to login form.
Added some comments and moved some elements around to group together
logically.