Bug#841491: Inject A Task for Generating Maven POMs

[Emmanuel Bourg]

This is an excellent idea, thank you for the patch! Maybe the plugin
could even generate the debian/<pkg>.poms file if it doesn't exist so it
can be picked up by maven-repo-helper at the install phase.

The code looks good to me, modulo some style mismatches (2 spaces indent
vs 4 spaces and imports ordering).

I would also suggest removing the generated .pom files automatically
during the clean phase.

Emmanuel Bourg