Fix missing Helper method in edit and use $EDITOR

* Fix the missing Helper method in the edit command to use Helper.HOME and the correct path assembly method (path.join) instead of joining strings together!
* Use $EDITOR instead of "vi" in the event a user doesn't have "vi" installed or doesn't understand it. Fallback to "vi" in case user doesn't have $EDITOR set.
Replace "vi" with $EDITOR in config command
Merge pull request #221 from wizardfrag/editfix

Fix missing Helper method in edit and use $EDITOR