Revert "Halfway attempt to get HTTP authentication work for the entire site (and not too slowly). Not sure this is the right approach."

This reverts commit db1b5d45693dcecefd9af7765200023a9569a36f.
Minor fixes
Added unique userid to User model; made this unique id the foreign key for opinions, instead of the real username
Now showing rant in overview screen
Made overview screen sufficiently sexy
UX and layout improvements
Made UX super-awesome by gradually adding UI elements after appropriate actions, but only the first time.
Move code around.
Layout: global max-widths.
Public link now available via URL
Fix all unit tests. Turns out the tests were buggy, but not the code.
Make public share-this-radar link available via modal dialog.
Fix login, also from explanation page
Rename index -> radar
Rename expl -> index
Prettier URLs