Add "Jira integration" to multiple projects at once

Description

At the moment (Gitlab CE 8.14) it's possible to add Jira integration only manually via WebUI per project, as I have for example about 40 projects which use the same JIra Project, it can be cumbersome to add it at once.

Proposal

Add Jira integration either per group (inherits all projects) too or via API, so it can be automated.

Links / references

https://forum.gitlab.com/t/automate-jira-integration-for-many-projects/5150