Version 2.1.0

This version is backwards compatible with 2.0.0.

All updates to the spec between release 2.0 and 2.1 can be seen here:
v2.0.0...v2.1.0
(This may include a few small commits after the actual release.)

From the changelog:

Documentation

1. replaced "hapi-server.org" with just "server" in URLs
2. clarified what the length attribute means for data parameters
3. clarified how to specify array sizes when one array dimension size is 1
4. more clarification and examples for error messages from HAPI servers
5. fixed multiple typos and made wording improvements

Schema

1. changed the definition of 'units' to allow for different units in the elements of an array
2. changed the definition of 'label' to allow for different labels for each element in the array
3. deprecated the use of all uppercase for the time stamp location options in favor of all lowercase, which is more consistent with the rest of the specification
4. now allow multi-dimensional data to not have bins in every dimension; any dimension with null for 'centers' and nothing present for 'ranges' will have no bin definition in that dimension

Server API

1. add HAPI 1411 error out of order or duplicate parameters
2. clarified server responses when time range has no data (HTTP status of 200 and HAPI status of 1201 and return no data content) or data is all fill (HTTP status of 200 and HAPI status of 1200 and return the fill values)