Fix system variable cascading and naming conventions

[matthewlarkin]

We have global variables set in the __bareStartUp() function. Ideally, we should have BARE_ prefixes for all of them and ensure robust cascading.

• setup BARE_ prefixes
• Ideal variable cascade:
  • __bareStartUp() default values
  • ~/.bashrc or ~/.bash_profile
  • host machine's variables otherwise set
  • ~/.barerc
  • $BARE_HOME/.barerc