Created rspec test for NetworkInterfaces ifcfg device name helpers

Purpose is mainly to cover current state regarding old even new naming
scheme.
Refactoring NetworkInterfaces helpers for parsing ifcfg device names.

These helpers are partialy incompatible with new naming scheme.
Fixed comments.
Fixed deleting alias assigned to device with new style name. bnc#846550
Removed some YCP -> Ruby artifacts
Updated changelog