[RFR] [Rest] #119 - removed dependency to backbuilder/api-client

Only ``BackBuilder\Rest\Test\RestTestCase`` and ``BackBuilder\Rest\Tests\Controller\UserControllerTest`` depends on 'backbuilder/api-client'. I removed it cause it's not used anywhere and the PublicKeyToken implementation changed.

We have to create a new issue to manage authentication of request in TestCase.