Apparently the nlohmann library is not available in the standard
repositories.  I would rather build it than add universe deps.

Update JSON build dependencies, change the dockerfile and other
CI files that relate to this.  Also update target mtxclient
revision.

- Update version numbers and documentation
- Fix github releases oauth key

Update .travis.yaml to have updated bintray api keys
Update bintray-release.json to have correct casing for repo

status to nheko-reborn matrix room

projects.

Update the appveyor configuration to no longer use mujx keys.

Travis-CI keys still need to be updated.

errors