Each resource in Heat has resource_mapping fucntion for loading his type
in environment for futher using.
This method should be callable and should return dictionary, where
key is resource type and value is corresponding resource class.
More over resource_type should have format:
"Platform Type"/"Service type"/.../"Resource Name"
This patch adds common test for this method and check all modules in
heat.engine.resources sub-directories.
Duplicate useless tests were removed.
Change-Id: I8148811418c21277a4b732de98a53c5291f57f1f
440a306216