Add parameter for max autocomplete rows, provide word searching

This PR does two things:
1. Provide a parameter in DBjoin to allow admin to decide how many rows of matching records to display.
2. Provide an additional search option "words" which searches for each word as a LIKE %word% and returns records containing all words.

This is a solution to request in http://fabrikar.com/forums/index.php?threads/display-full-list-of-results.35237/.