Encodes search URIs once, and only once.

Previous code was escaping pieces of the URI multiple times, so when an
advanced search was performed, e.g. "Release Title artist:Artist Name",
the URI would be encoded as "Release+Title+artist%25253AArtist+Name"
instead of the expected "Release+Title%3AArtist+Name"
Merge pull request #33 from ewollesen/master

Encodes search URIs once, and only once.