Add generalized and Neutron ReST client

The following ReST clients are added:

1) A generalized ReST client to execute operations on an API resources. The
assumption is that the operations on said resources are invoked as calls with
the format: list_<name>s, delete_<name>, show_<name>, create_<name>,
update_<name>

2) A ReST client that inherits from the generalized one and implements
operations for the following Neutron resources: networks, subnets and ports

This commit also re-structures the cloudcafe/networking directory to better
reflect the Neutron API's structure

Change-Id: I8c1cce5836f8e3be99e9965e2cb3ce1b622eda48
Merge "Add generalized and Neutron ReST client"