New nyserda elements

These are the changes requested in #6 and #8 to support the NYSERDA implementation. The elements added and the discussion about them are available on the issues linked. You can see [web schema documentation](http://hpxmlwg.github.io/hpxml/schemadoc/new_nyserda_elements/index.html) including these changes if that's easier to interpret as well.

requested reviewers:
@kmwoley
@andrulis 
@GamalielL

of course anyone else may review and comment as well.