Phone number parsing is overly simplistic

[m3brown]

https://github.com/cfpb/collab/blob/master/core/helpers.py#L34

Phone number parsing assumes the phone number is digits only, with no spaces, dashes, or periods. This would be find if the phone number was cleansed when created, but this is not the case.

Either:

1. Ensure the phone number is cleansed when saved
2. Have a phone number formatted that is more flexible