Reporting info on database contents

[tdudgeon]

The fragnet-search REST API responses should include information about the contents of the database. This should be extractable from the Supplier nodes, but it looks like the information needed by the user is not there. There needs to be at least a human readable description of the dataset, plus maybe info on the filters (max_hac and max_frag) parameters that were used in the processing and probably the number of molecules..

First we need that info adding, and then we need to collect it up and add it to the search results.