Uncap jsonschema
Uncap jsonschema

We have jsonschema capped at a fairly old version. Other than some
specific releases, it looks like keeping it below 3.0 was added in
I943fd68b9fab3bce1764305a5058df5339470757 without really any explanation
why.

In order to update to a 3.x release we need to:
1. Remove the cap from global-requirements.txt (see Depends-On), leaving
   upper-constraints.txt at a 2.x release
2. Remove the cap from all consumers (this change)
3. Release a new version of consumers that are published to pypi
4. Update upper-constraints.txt with those new releases
5. Update jsonschema in upper-constraints.txt to a 3.X release
   (See: https://review.openstack.org/649789)
6. Test consumers with the change from 5.
7. [Optional] fix issues in consumers that arise from 6.
8. Merge the change from 5.

Change-Id: I2d2ad4bbc7c54d3ff33deaa49553fc001f218316
Co-Authored-by: Sean McGinnis <961eeb09b6d45516665e15b82e013282c4faf575@gmail.com>
Depends-On: https://review.openstack.org/649669

openstack/os-net-config