Update marketplace.ini file if needed

For 6.0 and 7.10 branches, it is still necessary to increase the version before launching a build.

https://github.com/nuxeo/integration-scripts/blob/7.10/marketplace.ini
https://github.com/nuxeo/integration-scripts/blob/6.0/marketplace.ini

For example, if HF25 has to be built, the marketplace.ini first line should look like:

other_versions = 6.0-HF26-SNAPSHOT/TAG/6.0-HF27-SNAPSHOT

The script will:

1. detect the BRANCH based on the branch checked out for integration-scripts repository
2. check the latest available HF published on connect and check if the marketplace.ini contains it:
   • if yes then the marketplace.ini file will be updated by incrementing the other_versions property (commit needs to include the RELEASE ticket reference)
   • if no then nothing will be done

In both cases the script will return what has been done (nothing or an update).

Return code:

1. 0 in both cases
2. greater than 0 if any issue popped up during communication with github or connect for instance.

After implementation, this script will be added at the beginning of the following jobs:
https://qa2.nuxeo.org/jenkins/view/Depl/job/Deploy/job/IT-release-on-demand-build-nx60/
https://qa2.nuxeo.org/jenkins/view/Depl/job/Deploy/job/IT-release-on-demand-build-nx710/

A new variable for the RELEASE ticket reference will be needed.