TOSCA generator top level code

This set is invoked after the parser has created the TOSCA graph as the
intermediate representation.  It iterates over the TOSCA graph and creates
the graph for the Heat template.  It invokes the classes in the tosca
and syntax directories.

Partially implements blueprint heat-translator-tosca
Change-Id: Idbbbf2a9992ffac51bdaf93a68039b0fecc928dc