python3: Add basic compatibility support

Use six.iteritems to replace dictionary.iteritems() on python2 or
dictionary.items() on python3.

Change-Id: I623009200f3a90985a2c0178673df7d54b36a686
Signed-off-by: Chuck Short <chuck.short@canonical.com>
Extract basic request call

Create a function out of the standard request call that handles common
headers like user agent and logging.
This makes future changes easier to digest.

Change-Id: Ia25f997df64efdce27c8fb815e544922940145c3
Add a get_data function to Service Catalog

Service catalog takes as a parameter the entire token. This makes it
difficult to extract only the service catalog component without querying
the catalog version, which should be unnecessary.

Change-Id: I3ad428fcb3279e8aa607f67f58265a085ae63440
Merge "python3: Add basic compatibility support"
Merge "Extract basic request call"
Merge "Add a get_data function to Service Catalog"