fixed experiment data path
Merge pull request #216 from rmarianetti/fixExpDataPath

fixed experiment data path
No longer depend on NTA environment variable in order to fix issue on Jenkins
Merge pull request #217 from rmarianetti/npc-73

No longer depend on NTA environment variable in order to fix issue on Je...
revert to AC_DEFINE _PY27, fix Python2.7 not found problem

semi revert f894c147 and use AC_DEFINE _PY27, fixes NPC 345