Allow more word variants in search

[ascheman]

From @dasniko on March 25, 2017 13:59

Currently, the "Code Golf" activities can only be found when the term code-golf is entered exactly like it is represented in the data (or fragments like code or golf).
It would be nice to find the activities also when entering codegolf or code golf.

This would be a benefit not only for the Code Golf activity, but also for all other talks/activities which deal with word variants and/or composite words.

Copied from original issue: dukecon/dukecon#36