Add development and CI configurations

- Add support for Travis CI and test under Plone 4.1 (Python 2.6), Plone 4.2/4.3 (Python 2.7)
- Add support for Coveralls
- Add support for code analysis
Add missing IGallerySettings import on test
Fix package distribution

- Fix package classifiers
- Fix package dependencies
- Drop support for Plone 3.3 and Plone 4.0
Clean up MANIFEST.in
Merge pull request #36 from collective/hvelarde-travis-ci

Implement CI and QA