[web] Decode bytestring to unicode in get()

I've noticed this began to become a problem for many modules,
so instead of decoding it in the modules, it made much more sense
to decode it in web.get()

Fixes #532
[wikipedia] Fix wikipedia search for Python 3

.keys() in Python 3 returns something that is similar to a set,
and thus not indexable. Converting it to list fixes the problem.