Fixes if statement inefficiency in quantum.agent.linux.interface

Changed logic of checking the existance of a port value

Change-Id: Id06447a753fd0201ef44a047657bd747ce18d546
Remove redunant key list generation in Cisco plugin

Evaluates existance of key directly on dictionary.

Fixes bug #1110957

Change-Id: I9b46a991ab9c764d7451cc122d208e06778c1ee1
Merge "Remove redunant key list generation in Cisco plugin"