[PRD-2288] Fix null value in 'mac' or 'id'

Check 'mac' and 'id' fields of agent request data for emptiness.
Do not overwrite 'id' for node.
Do not allow 'mac' == None
Tests added.

Change-Id: I8d31d7669eaf78e8c40022b21ef2387723f66d45
Disable web.py debug mode in case of production
PRD-1855

Change-Id: I0ab96c03675ca6e71e9906e8527f1e229a1d6767
Run shotgun unittests, run flake8 on every python file

Change-Id: I31d3a8c32a4acbc5a99d766f1842bbb748ddaf60
added ntp module

Change-Id: Ifcf09a5eb9e2dee68a966083067d3f30d27542d7
clean up error text, bad errors in logs

Change-Id: I5b4e5cd986d9312982c80373b49199fbb2ba4363