WCP-345 : Adjusted the web service interface for telephony

There were a couple features we were unable to test while telephony was disabled on the Blackboard side.  Now that it is enabled we noticed some differences in our assumptions.
- non-chair phone is required
- SIP phone is required
- SIP phone has to be in a weird format (sip:foo@example.com)

I changed the errors that come back from bbc web services for telephony to display to the user for now as they are validation errors. There is a separate issue (WCP-344) to validate the data before it hits the web service.