Adding logs to tasks

Logging is currently missing in the REST api layer in v2/tasks

Related to bug 1267213

Change-Id: I608390a7be1b2b02f281d974bd456a8e9e7897f7
Cleans up imports in models.py

Some of the imports were placed in incorrect order.

Change-Id: I14555b5c3bd6871d4b1e0cea7e03c191ffd6cf33
Merge "Adding logs to tasks"
Merge "Cleans up imports in models.py"