Switched login to use WTForms

Removed DbUser class, updated tests, added g.user
Changed password reset process to WTForms, updated tests.

Yes, it was painful.
Converted new user form to WTForms
Converted new request form to WTForms
Converted new event form to WTForms
Converted Event edit form to WTForms
Fixed test harness
Separated username and email errors in new account creation
Events and requests now display in order by date
Merge pull request #34 from kevana/forms

Switch to WTForms