Session.get_token() wasn't properly deprecated since the deprecation
was only mentioned in the docstring. Proper deprecation requires use
of warnings/debtcollector and documentation.
Also, changed a test to use the non-deprecated function instead where
the test wasn't checking that the deprecated function worked.
bp deprecations
Change-Id: I3d421b35554d58476281e037f90ab9b48e82730a