rootcoredir -> rootcorebin

with the analysis release installation rootcoredir points to the
directory on cvmfs, not to the local installation dir.
import_SUSYDefs_enums: do not crash on missing enum

some enums are temporarily removed (do not know yet whether we will
need them). Do not crash on them.
utils.load_packages: use macro from Rootcore

The previous implementation (loading 'by hand') was simpler,
but it does not work anymore with the analysis release setup.
Merge pull request #39 from gerbaudo/xaod-fix-pyscript

Xaod fix pyscript