Added the `RequestLog` Model to the possible exports

Added `gzip`, `tgz (tar.gz)` and `tbz (tar.bz2)` to compression methods for exporting
Added mime-types for the contents to the response.

Changed rendering in an abstraction method `_render_json`,
to implement further render methods for `protobuf` or other similar structured datatypes.
Merge branch 'develop' into export-requestlog
Missed the changes in the template to use new exports.
Merged the changes from the `adhocracy.hhu_theme`.
Merge branch 'develop' into export-requestlog
Removed the "csv" option from the formencode, the code responsible to handle this option is thrown out, due to nested dict structure of the export data, that the "csv" format not easily could represent.
use assertEqual instead of assertTrue)
Update to Python 2.7.5
buildout: removed option environment-vars, this option is not supported by buildout >= 2
Fix pep8 test by just searching just below src/adhocracy
Fix badge tests after shibboleth changes (fixes #395)
Merge branch 'develop' of github.com:liqd/adhocracy into develop
Fix: thumbnail tests are broken #377
make sure buildout does not build Pillow, the python build takes care for this dependency
Use ; instead of , for Shibboleth multi value fields

This corresponds to what mod_shibboleth does.
Update lxml from 3.0.2 to 3.2.1
Fix postgresql-initdb buildout part
Fix OpenID login (#416)
OpenID selector: Clean up
Move OpenID selector stylesheet into main stylesheet pipeline
[openid selector] move JS into main pipeline as well