Updated documentation examples for attributes and Metadata

This provides fixes to documentation for various metadata usage examples
as well as detailed examples of usage for Resource attributes.
Normalize quotes

- Single quote for strings, double quotes for docstrings
Super-prviate method now merely private

- I don't see that this method needs name mangling to succeed,
  am I missing something?
Developer docs, minor tweaks
Merge remote-tracking branch 'upstream/pr/19' into develop
No more sphinx warnings!