Raise an exception when quota config parameter is broken

Function get_remaining_quota returns None when quota config
param doesn't match a pattern (i.e. it's broken). It messes up 
the logic of its callers and leads to unpredictible behavior of 
the entire system.

This code raises InvalidOptionValue exception if config is broken

Change-Id: Ib08d2114f460d127aacf580fc519a58d6e8eba16
Merge "Raise an exception when quota config parameter is broken"