consoleauth: retain havana rpc client compat

48dd52095869d36970de232f5dfa60656fcd578b added v2 of the consoleauth rpc
API and made the client side use it.  However, I forgot to leave in
support for talking the havana API on the client side.  This is needed
for rolling upgrade support.

Related to bleuprint rpc-major-version-updates-icehouse

Change-Id: I30f5651b3f83dcc25639a01513987798a6cdcbb8
Merge "consoleauth: retain havana rpc client compat"