Add license information to pom file

[ptrkaz]

Currently, the resulting pom.xml file of the library is missing information about the license, which leads to issues when using tools that would benefit from retrieving that information.

It would be great if license info could be added to the file.
One approach could be to add the pom {} block to mavenPublish in gradle.

[hannesa2]

please see #504

[ptrkaz]

Wow, thanks for looking into that so quickly!