iproute2 tools implementation

uses 'ip', 'ovs-vsctl' and 'dhclient'. Includes the ability for
mocking/dry-run by passing 'mock=True' to apply. This will create
and return a string with the commands to implement the required
configuration.
Adds mock ability to the ENI and Ifcfg providers

Specifying mock=True for 'apply' will return a string
representing the changes required, or commands to be used
in order to implement the requested/specified configuration.

This is also exposed to the cli, with -m (--mock), e.g.

os-net-config --mock -c ./etc/example_os_net_config.json -p eni