Nifi Registry - Git integration

NiFi Registry +Git integration.

If we have some pre-commit/merge rules enabled on Git side (like check commit message to include Jira number) - it is completely ignored by NiFi Registry. This means that if rule didnt pass and no changes was committed to GIT - Registry 

• dont show error message
• save data to Registry

Possibly will be helpful to have following

• setting - [Save on GIT fail]- if TRUE and GIT commit fails - do not save to registry, if FALSE - current behaviour
• pass back GIT error message to NiFi UI