Updated to OpenSlides 1.5

- Fixed get_option_id function.
- Fixed overlay message, poll form and alert message.
Code improvements for next 1.0.4 release.

- Added README with Changelog.
- Added requirements files.
- Changed to MIT license. Removed old license header.
- Updated setup.py
- Added fabfile and tests. Fixed pep8 errors.
- Clenup old TODOs in code.