xclip is necessary for pass(word-store) to send passwords to the
clipboard / X-selection, rather than echoing to the terminal.
The option currently defaults to false, because someone may not want the
dependency on X libraries and also pass is really quick to build (it's
just a shell script).
pass is just a simple script to store passwords encrypted via gnupg in
a git repository. It uses many other tools, and until now relied on
them being in PATH.
This commit wraps the script and sets PATH.
