complex search options

[CarlFK]

This keeps happening: "I remember this video I saw, I want to see it again.. What was it called? I think it was at PyCon 2011 or 12... by Jeff I forget his last name." And then start typing stuff into the pyvideo search dialog, and getting lots of hits.

The existing search and such are good for one class of searching, but an advanced search would be good. I can think of lots of elaborate searches, like being able to pick the operators (and/or) but I think a list of fields from the video model, user enters text into a few fields and they all get and-ed together is fine for now.

[squiddy]

This sounds similar to #88. Just mentioning it because both features might overlap.