Add Finddistro.cmake for python distro package
Introduce Finddistro.cmake to find distro python package which was introduced in LCG_100_ATLAS_3.
Tagging @akraszna to check if all looks fine.
Introduce Finddistro.cmake to find distro python package which was introduced in LCG_100_ATLAS_3.
Tagging @akraszna to check if all looks fine.