Removed references to jQuery from tests.

Assets test still referenced jQuery which was removed in commit
06d4bc8b84088. This caused tests to fail with:

     FAIL (0:00:00.058) includes full library
          Failed assertion, no message given.
        @ /home/mike/.rbenv/versions/1.9.3-rc1/lib/ruby/1.9.1/minitest/unit.rb:185:in `assert'
          test/integration/assets_test.rb:9:in `block in <class:AssetsTest>'


The test suite is now passing.