Prepare Mg SR1 release

Prepare the MAgnesium SR1 release .

This means to:

• cherry-pick related bug corrections from master , improvement on OTN and T-API are concerned
• update project version in poms
• update dependencies

https://docs.opendaylight.org/projects/integration-distribution/en/stable-magnesium/platform-versions.html

• update others environment parameters e.g. for lighty.io and tox

Once that done, the release must be staged in Jenkins and then officially released using the self-service process

https://docs.opendaylight.org/en/stable-magnesium/release-process/project-release.html

This last task can only be performed when all upstreams dep are ready i.e. when all managed projects have been released (prevision date 04/20/2020).
The deadline is one week after all managed projects have been released.

Evaluation indicators:

• cherry-picks from master done
• magnesium stage release job OK in Jenkins
• tpce artifacts published on nexus