revised api to conform with revised resource types

That goal of this branch was to revise the yaml file describing the API of our metadata index to reflect the changes in the 'resource type' entry of our meta data scheme. In particular, this refers to the revisions to resource type to facilitate a faceted search.

While changing the yaml file two other revisions were made that reflected earlier revisions to the code but were not yet updated in the API. These changes were the number of recognized resources types, which was increased from 11 to 14 at some earlier time and the other entries in our meta data scheme which were already available as a faceted search, namely 'topics', 'licenses' and 'provenances'.