Tool to package LCG RPMs to a tar file

Initial version of the tool. It takes as argument:

<project_name> <version> <cmtconfig> <external list file>

Where the external list file has the syntax:

 {
          "heptools": {
            "version": 84
            "packages":[
              "AIDA",
              "Boost",
              "CLHEP",
              "COOL"
            ]
          }
 }