Add Bundle-License Header to Nebula bundles

[laeubi]

Bundle-License` is a standard OSGi Header, for better compatibility we should add one to each published bundle.

My idea would be to add a license to the pom this should then be automatically be translated by tycho to the appropriate header.

As far as I know, there is currently no such feature in tycho, so this ticket could act as a starting-point to add such feature to tycho.

[lcaron]

Issue closed, thanks @laeubi & @wimjongman