Sample thin interface

Here is an example of a thin interface for the SDK.  We aren't
making any resources here, it is all dictionaries.  Assuming we
have a session:

    from openstack.network.v2 import thin
    requests = thin.Thin()
    for dictobj in requests.list_networks(session):
        print(dictobj['id'])

Obviously, the thin layer isn't doing much, but it does provide
a simple interface to access the methods.  There may be cases
when it would need to do more.

If we go with this approach, we'd just neeed to be sure that if
a resource needed special handling for an operation, we override
the class method rather than the object method.

Change-Id: I2b41ad64348802f6461abfd39a157e808686bb4d
Implement iterator paging

Instead of manually passing in limit and marker, automatically set the
marker to the end of the received data and continue requesting data
until none is returned. This is a naive implementation as it doesn't
attempt to know when it has received all of the data without making one
request past the end, as pagination is implemented in several different
ways across the services. Optimizations to reduce that extra call should
probably be implemented per-service due to those differences.

Change-Id: I63a8eb7836c1a614e4bc2ee98fa93f239b343cbb
Merge "Implement iterator paging"
Merge "Sample thin interface"
Correct the namespace for Server resource

(this also removes a stray incomplete sentence)

Change-Id: I00de58befa14c6a9d92dcfb58f7bea1285beeab6