- use the new fact that datadirs are in the gp_segment_configuration
- fix a few things with the gpperfmon behave tests (mostly for macOS)
   --> the change to mgmt_utils.py is to do the config file manipulation
   natively in python
   --> the change to the gp_bash_functions.sh is to use ASCII '
   characters so that python string comparison is happier

Author: C.J. Jameson <cjameson@pivotal.io>