Description of problem:
Errors creating lab controllers are not handled properly

Version-Release number of selected component (if applicable):


How reproducible:


Steps to Reproduce:
1.go to /labcontrollers/new
2.Enter details, ensuring to use an email address that already exists
3.Save
  
Actual results:

500 ISE


Expected results:

It works


Additional info:

the save() method in bkr.model.labcontroller uses the edit()
method as an error_handler. The edit() method expects a valid LC id,
and if you fail to create an LC you don't have one.