Add support for prev/next/self links when returning paginated results. To do this: 1) change "data" envelope from an array to a dict 2) move the "data" array to the "collection" property, which is an array of elements in the collection. 3) add @links dict keyed by link relation: self, next, prev. Each relation is an array of dicts with uri and rel keys. In this case there is only one element, but there is nothing preventing a relation from having multiple url's. So this follows the formatting needed for the general case. Relations are present only if it makes sense. So first page has no prev and last page has no next. 4) add @total_size with number of element selected if they were not paginated. Replicates data in X-Count-Total header. Changed index to start at 1. So the first page is page_index 1 and not page_index 0. (So I am no longer surprised when I set page_index to 1 and am missing a bunch of records 8-)). Also a small fixup, json response ends with a newline so printing the data, or using curl makes sure that anything printing after the json output (like shell prompts) is on a new line. Tests added for all cases.

--- a/CHANGES.txt	Fri Mar 08 22:30:11 2019 -0500
+++ b/CHANGES.txt	Sat Mar 09 11:06:10 2019 -0500
@@ -61,6 +61,10 @@
    - If dict2xml.py is installed, the rest interface can produce an XML
      format response if the accept header is set to text/xml.
      (See: https://pypi.org/project/dict2xml/)
+   - When retrieving collection move list of collection elements to
+     collection property. Add @links property with self, next and prev
+     links (where needed). Add @total_size with size of entire
+     collection (unpaginated). Pagination index starts at 1 not 0.
   (John Rouillard)
 - issue2550833: the export_csv web action now returns labels/names
   rather than id's. Replace calls to export_csv with the export_csv_id