Remove reference to grokengine-default.xml config file, not relevant to NuPIC,
reverting 24b16d61594b5125471bd6eb061b089abdaf19c7 in the process.  Fix
super() calls in py/nupic/support/configuration_custom.py
Fixed example OPF command on README.md; referenced unset environment variable $NUPIC_HOME
Adds environment setup script to installation.
Adds region unit test.