Neon support + Jazz SCM Fix

[jjakub]

We're using the Activiti Designer on a project, and I've been unsuccessful in installing Activiti Designer on Neon, and then again, when saving/loading files that reside in IBM Jazz SCM (Rational Team Concert). These should fix both issues.

[salaboy]

@jjakub thanks a lot for this PR. I will assign it to @balsarori to review and merge.
Are you using this designer heavily? it will be interesting to understand what kind of use cases do you have to see if our new approach for the modeller will work for you.

[salaboy]

@balsarori can you please review and merge if it is ok?

[salaboy]

@jjakub I think that you need to sign our CLA.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.

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