Added Travis continuous integration to the project.
Improved README.

- Improved wording;
- Fixed #39;
- Added banner for Travis CI.
Added website_requirements.txt.
Improved settings.py to work when settings_local.py doesn't exist.

- Improved previous fix of issue #39;
- Added documentation to the settings;
- Made settings_local.py optional. Falls to DEBUG mode if don't exist.
Fixed #44 -- Made entities.tender.feed show the correct tenders list.