Change packaging references to python-saharaclient

Now that the git repo has been renamed, all references to the project
in the packaging code have been changed to 'saharaclient'.  It will
now install as python-saharaclient but still retains /usr/bin/savanna
and site-packages/savannaclient for legacy code support.

Partial-implements: blueprint savanna-renaming-client
Change-Id: Ib1d3022dffb2fa7319dd51ecad6c6d7072915472
Change internal variables and classes to 'sahara'

Change any and all internal variables, contants, or class names
to reference "sahara" rather than "savanna". Also remove 'Savanna'
from NA comments marking intentional divergence from the nova client.
Map the 'savanna_url' param to 'sahara_url' in the savannaclient to
make sure the change in saharaclient.api.Client.__init__ does not
break existing code.

Partial-implements: blueprint savanna-renaming-client
Change-Id: Ia537a4d43036b44c05a399de0d04482e6029c6bc
Merge "Change packaging references to python-saharaclient"
Merge "Change internal variables and classes to 'sahara'"