Couple of billing report fixes.

No longer display languages that aren't completed.  I was including
these in the list in case they were completed, then flaged incomplete,
and no billing record was created.  But the much more likely scenario
is that they were simple never complete.

Optimized finding languages without billing records a bit.  Now we
only do one query to find them all.

Don't include languages that have billing records, but the records are
out of the date range.
Billing report form improvements.

Changed team select to using checkboxes.  Changed type select to using
radio buttons.  Made the default type the new type.
Better layout for the billing report.

Removed id=login.  Not sure why that was there, but we don't really
want to imitate the login form.  This adds more space for team names.
Went back to a selectbox for the report type, the radio boxes weren't
looking good after the switch.
Use billing records to populate the billing report form

This is better than video activity, since it's possible no videos were
added for a team, but a bunch of languages were completed.
update tests for billing ui changes
Merge pull request #862 from pculture/billing

Billing