Merge pull request #39 from wardi/master

Metadata Schema: start of tag vocabulary work
metadata_schema: map dataset url to program URL instead of data series url
metadata_schema: temporal_element
metadata_schema: the_geom
metadata_schema: remove supplemental_information
metadata_schema: new proposed_schema.xls
metadata_schema: language and author_email were removed from proposed
metadata_schema: documentation_url and related_document_url
metadata_schema: endpoint_url