write custom inventory scripts to AWX_PRIVATE_DATA_DIR
write custom inventory scripts to AWX_PRIVATE_DATA_DIR

this makes it so that custom inventory scripts can access credential
files laid down in `/tmp/awx_N_<xyz>`

see: https://github.com/ansible/tower/issues/2951

wwitzel3/awx,wwitzel3/awx,wwitzel3/awx,wwitzel3/awx