Added Travis CI Support

Tests are run on all Travis supported versions of Python.

test.py contains 3 tests:

    generate_json:

        Generates the json data from all the plugins
        and asserts that all plugins are accounted for.

    generate_zips:

        Generates zip files for all folders and asserts
        that all folders are accounted for.

    valid_json:

        Asserts that the json data contains all the
        fields for all the plugins.
Fixed isinstance testcase

Replaced the unicode_or_str hack with the basestring class.

Used assertIsInstance()
Added unrequired files to .gitignore
Merge pull request #2 from musicbrainz/travis

Added Travis CI Support