Restore SQLite Full Text Search Support
It's back!  0519ac68246a3a73aca9e653c1841183642061fd

I mostly upgraded this from the old code, and still have some cleanups planned so be warned, the API may change a bit!

There [used to be](http://charlesleifer.com/blog/using-advanced-database-features-with-peewee-a-python-orm/) support for FTS3/4 in SQlite, but it went away some time.

Bring it back, for great justice!
