[RFR] Add project configuration to API model

- [x] Add configuration item
- [x] Add previous analyses hashes
Fabien does not like badges in the readme. He always rejected them for Sensiolabs and Symfony repos.

and the URL of the badge is outdated (secure.travis-ci.org is not needed anymore since more than 1 year to have SSL, and they provide better SVG icons). If you really want to add the badge, you should get the uptodate snippet from Travis (and it should probably not be part of this PR but of a separate one)