Added more file preview icons
Fixed #130: Project stats crossing accounts

This is a hack. It works. But it still feels like a hack. The account_id
is added directly to the parsed query string. It does stop project stats
from crossing accounts. So it works.
Resolved #133: Project balance and unbilled
Resolved #131: Cache docs count in memo

Cache the number of uploaded docs into memo.
Counter cache, project balances, bug fixes