Ensure smartics-jboss-modules-maven-plugin changes are merged upstream

[jamesnetherton]

Smartics finally have their latest plugin code on GitHub:

https://github.com/smartics/smartics-jboss-modules-maven-plugin

I agreed that I'd send a series of PRs with the changes that we have made so that the code can be reviewed.

Since we've invented an entirely new XML schema for the plugin, I think it's only fair that we:

1. Document it and back up with an XSD.
2. Add appropriate integration tests

If the changes are accepted, hopefully we can get a new plugin release and switch to using the upstream version.

[jamesnetherton]

Initial PR sent for addition of the V2 module schema smartics/smartics-jboss-modules-maven-plugin#4.

The other fixes and enhancements hang off of this so there is little value in creating PR's for those until this change is merged. Therefore, marking this issue as blocked for now.

[jamesnetherton]

Closing this. We've got all of the core functionality needed for us to switch to the upstream plugin onto upstream/master now.