Find libraries in the usual paths, also

This should fix any build issues on OS X 10.9.
Use bundler, not jeweler, make a static gemspec

This makes rake test trivial to run, and feels just a tiny bit less
insane.
Add rubygems as a source to gemfile
Add rake as a dep
Fix cleaning & building the ext before testing
Don't explicitly set library paths for tests
Add ext to require_paths, remove lib/
Actually return a value from unicode_transliterate

This caused segfaults on LLVM.
Make to_utf8 able to cope with arbitrary-length strings
Merge pull request #3 from antifuchs/asf-library-paths

Library paths & C compiler fixes!