rework PatientGenerator, add TestPatient

This is a rework of the way test data is generated for the register-patient test. I introduced a TestPatient class that just holds the raw data for a single Patient. I changed PatientGenerator to return an instance of TestPatient. And I moved code related to test data out of the RegistrationPage into the RegistrationAppTest. The RegistrationAppTest runs ok for me with a local vagrant vb with both Firefox and Chrome. 

Still TODO: the phone number; also we should strive to remove the xpath expressions, but that will require application changes.