break out console into separate design document

This moves all the static content for the console (the part where you log in, create encounters, and choose tasks) into its own design document. The login page is now `/tabcat/_design/console/login.html`; the old login page simply redirects to the new one.

In addition, functions in `TabCAT.UI` that were only used by the console have been moved into `TabCAT.Console`, which lives in a separate JS file only used from the console.

I'm mostly looking for hand-testing to see if I broke anything, and some sanity-checking of my code.