WIP - RPM packaging done with Maven

Packaging directly from Maven introduce quite a few benefits :

* versioning can be coherent between pom and RPM
 * RPM can be attached as build artifact and uploaded with the results of the build
 * Maven release plugin can be used to ensure coherence of releases
 * ...

Introduce appassembler maven plugin to integrate TanukiSoft java wrapper (because no Java daemon should be left behind).

Minimal RPM created from this. Not all functionality have been ported, some on purpose (GC tuning should probably be left to the end user, not much chance that generic optimizations make sense in all cases) some by ignorance (I'm not a very good packager).

Note that this is work in progress and needs comment / rework before merging.