Add ResultsExist

The included test actually does not pass.  I'm not sure if it's an issue with SQLite?  The same code works fine on Pg where I'm using it at $work.  So, I'm actually looking for feedback rather than a merge, but the pull request seems the best mechanism for this as I'll likely lose track of it otherwise.

Also, according to this, a LIMIT might need to be applied in cases of SQLite?

http://stackoverflow.com/questions/9755860/valid-query-to-check-if-row-exists-in-sqlite3

Feel free to reject/propose better names etc.