Add unit tests for guestagent.models.py
Delete guestagent.utils.py since it is no longer invoked anywhere.

Bug # 1090139

Change-Id: Iad3fad6f2b5bdb813b499dc8ce7181e6f8fb0231
Merge "Add unit tests for guestagent.models.py Delete guestagent.utils.py since it is no longer invoked anywhere."