uses system instead of exec
uses system instead of exec

Issues:
- git fetch --all creates a child process + hangs
- error messages from git remote

Solution:
- use system instead of exec
- redirect error messages to /dev/null instead of adding code to check if remote exists

read more http://stackoverflow.com/questions/18556090/back-tick-in-ruby-does-not-work-with-tail-f-command

hbt/github-backup