Revert "Big Switch: Check source_address attribute exists"

This reverts commit 0dde14c0cd6ffea8ebff715342852ef17a9c0b70.

This fix only addressed part of the problem. The socket call
in python 2.6 does not accept an extra source address arg
either.

Change-Id: I4df4f66e9db0da1a8923ee37e918718f3bcf26ee
Partial-Bug: #1316382
Merge "Revert "Big Switch: Check source_address attribute exists""