Add missing groupIds in pom files

Missing groupId cause the tycho-set-version plugin to fail with an NPE,
see https://dev.eclipse.org/mhonarc/lists/tycho-user/msg04571.html
(cherry picked from commit 2127604a31932b60bef9ce4335a21b8fcf18c0da)
Bump Tycho version number to 0.19.0
(cherry picked from commit cbec3e6fb263eedcda3311a72190ac96ad463cb8)
Helper script to bump the version number.

This script automates up to a point, but some updates need to be done
manually:

- <parent> tags that refer to the root pom.xml (without a relative path)
- features.xml files that get auto-generated based on templates in resources/
Merge pull request #643 from dragos/improvement/set-versions

Make bump-version a simple(r) operation