GUI Connection when using SSH X11 Forwarding

[tomeichlersmith]

Describe the bug
Authorization is not allowed when attempting to run xeyes from within a container after connecting over SSH to a server.

To Reproduce
On some server.

$ ssh -XY my-server
$ cd path/to/clone/of/denv
$ ./test/gui/run-gui-test
X11 connection rejected because of wrong authentication.
Error: Can't open display: localhost:10.0

Expected behavior
I would like to be able to X11 forward from the container over SSH to the user's host computer.

Additional context
Add output of denv version and denv config print here.

v0.8.2-23-gd540d11

(i.e. found while working on #124)