TOSCA definition types for TOSCA library.

Create a TOSCA metamodel covering various TOSCA types including node type,
relationship type, capabilities type, interfaces and properties.

Also, a small change, renamed heat-translator subdir to 'translator' as tox
doesn't like dash in the name.

Change-Id: I59e496063f8f1d7fd8557278a690b65d2a400a43
Partially implements blueprint heat-translator-tosca