Fix heat hint file reading to work properly

Heat does not give us the exact API version to request, so we must infer
version 1 (/v1/) since that is what we speak. The other test cases are
all updated to use /v1/ too, so that the fakes can remain the same.

Change-Id: Ifb74546db16836aaa67fdd647aad2c5cf8aa84b4