Songkick: Exit early for empty strings.

Also exit early if lat or lng is not available.
Songkick: Rename songkick_event.handlebars to songkick_geteventid.handlebars
Songkick: We shouldn't exit when we find "the area".

Brad was right all along.
Songkick: Now works for countries.

"concerts in spain" and "concerts in the philippines" should now work.
Songkick: "concerts in london" not working.

o.performance can be an empty list so we put a condition to check that.
Songkick: Filter out unknown venues and events with no artists.
Merge pull request #371 from duckduckgo/jag/songkick

Songkick: Exit early for empty strings.