Add p2-admin submodule
Build p2-admin command just after configuring eclipse
Cosmetic
(orcc_build) Update the process used to build orcc

 - No more build.properties used, everything is configured by passing command line arguments
 - Some folder names have been updated. This should not cause any side effect
 - At the end of the build process, no p2 repository is created
   + A zip file containing only plugins/features folders with jar file is created
   + We have to build repositories manually
(orcc_build) Create the p2 repository after the build
(build) Complete the process of making repositories

Features are associated to a category
The oldest builds are cleaned automatically
A top level composite repository is initialized
(orcc_build) Compress everything on generated p2 repositories
(orcc_build) Use a variable for orcc default feature name
Merge branch 'p2_repo_improvements'