First AxstradPageAdminBundle commit

The tests do not pass.
Merge branch 'develop' into feature/page-admin-bundle
Register PageAdmin class with Sonata admin.
Catch all route should be last
Fix PageAdmin's namespace.
Fixes for PageBundle tests
Merge branch 'develop' into feature/page-admin-bundle
Fix testContentEdit
Merge branch 'develop' into feature/page-admin-bundle

Conflicts:
	composer.json
	composer.lock

Had to limit Symfony version to <2.6
Add Doctrine ORM annotation mapping to Page entity.
Correct Admin create test assertions
Make Admin create test pass
Merge branch 'feature/page-admin-bundle' into develop
Don't use trait to implement SeoAwareInterface
Refactor the repository's ORM entities
Remove unneeded Axstrad\Content models
Run console commands quietly by default
Remove Sluggable MethodsTrait and PropertiesTrait
Update documentation