Adds client certificate to testing request.
Removes testing only contructor on Request
Adds a testing certificate to the resources
Adds functions to browser to add certificate

-the embeded one
-from byes
-from store
Given, When, Then
Cleanup according to @thecodejunkie

Adds another over load to add a cert to the testing request.
Merge pull request #1215 from albertjan/ClientCertificate-Testing

Adds client certificate to testing request.