Description of problem:
Sometimes cumin reports 
'INFO Response 500 Internal Error'
in the web.log. It would help debugging if in such case cumin also record the traceback in the log. Then engineer can evaluate the severity and the cause of the issue.

Version-Release number of selected component (if applicable):
cumin-0.1.5786-2 

How reproducible:
Very low

Steps to Reproduce:
1.Install cumin according to documentation.
2.Log in cumin as administrator.
3.Click on configuration tab.
4.Create new tag.
5.Add host localhost to the created tag and feature NodeAccess.
6.Try to activate wallaby configuration.
7.Activation fails - that's ok.
8.Delete created tag.
9.Create new tag.
10.Add host localhost and feature BaseDBVersion.
11.Activate wallaby configuration.

Actual results:
INFO Response 500 Internal Error

Expected results:
DEBUG Exception in wooly/server.py, generating redirect or Internal Error
Traceback (most recent call last):

Additional info: