Do a proper script execution via #!/usr/bin/env

The invocation of a bash script with an absolute path to bash can cause problems on systems with a non-standard non-standard file system layouts.
To overcome this issue, use '#!/usr/bin/env'.
Good bash best practice source: http://andreinc.net/2011/09/04/bash-scripting-best-practice/
Merge pull request #1 from dol/patch-1

Do a proper script execution via #!/usr/bin/env