Enable highstate failure retcode

- new config variable to enable/disable the new functionality
- added new function to determine if the highstate return data indicates
  an error or failure has occurred.
- added new logic to the end of the salt cli call that if enabled using
  the config variable, determines if salt should exit with a non zero
  exit code and then will exit if any failures or errors are found in
  the highstate return data.

Should fix issue #7013