Add exposed filters to project listings

[jenlampton]

Suggested filters for the modules page are module 'packages' from info file: like Administration, Education, Commerce, etc

parent issue: #95

[docwilmot]

can we do #100 so we can actually get good info about modules?

[laryn]

If "Packages" end up getting removed, this feature would still be important but using "Tags" as the exposed filter.

[ghost]

Closing in favour of #442