Restrict Releases to Master-Branch Updates

[AndreG-P]

@physikerwelt Could it be that you forget to update the POM-versions (or we forget to specify that in travis)? vmext-demo depends on v. 2.0.2
https://github.com/ag-gipp/vmext-demo/blob/9a27896a1242d823d13f1161f49066c801c218ad/pom.xml#L61-L65

but all poms are still on 2.0.2-SNAPSHOT:
https://github.com/ag-gipp/MathMLTools/blob/77c69b6366a5b8720796d1cd9d155ba26c2f1b20/pom.xml#L9

Also, the releases are already on 2.0.4: https://github.com/ag-gipp/MathMLTools/tree/2.0.4
as well as maven central: https://search.maven.org/artifact/com.formulasearchengine.mathmltools/mathmltools/2.0.4/jar

Something we missed in .travis.yml?

[physikerwelt]

master seems outdated. Mvn central releases correspond to GH tags

[AndreG-P]

@physikerwelt
Got it.

I would like to keep it open because none of the other branches are ready to merge to master now (test fails). Also, why do we deploy on non-master branches? Isn't that a mistake?

[physikerwelt]

The problem is that I was stuck in #34 and am still waiting for a reply there.

[AndreG-P]

Sorry I missed that request. Thanks for pointing it out again.