Add 'ip rule ...' support to ip_lib

This change adds 'ip rule add', 'ip rule delete' and extends the IpRoute
class to support more ip commands

Change-Id: I8ba2f2d2ee896d9f4a378570be1524077d5b663c
Partially-Implements: blueprint neutron-ovs-dvr
Merge "Add 'ip rule ...' support to ip_lib"