Proper deprecation for client.HTTPClient
Proper deprecation for client.HTTPClient

client.HTTPClient wasn't properly deprecated since all it had was
a comment in the code. Proper deprecation requires use of warnings
and documentation.

bp deprecations

Change-Id: I1c50c1441b23a79831e6e1df749084130e4b9af7

sdpp/python-keystoneclient,Mercador/python-keystoneclient,Mercador/python-keystoneclient,sdpp/python-keystoneclient,magic0704/python-keystoneclient,klmitch/python-keystoneclient,klmitch/python-keystoneclient,magic0704/python-keystoneclient