Apps sometimes requires DBUS socket address to run properly

Signed-off-by: Peter Lemenkov <lemenkov@gmail.com>
Setup DISPLAY environmental variable for d-bus

Sometimes it will start apps which requires DISPLAY since they have to interact
with user.

Signed-off-by: Peter Lemenkov <lemenkov@gmail.com>
GNOME keyring requires gcr-prompter

Signed-off-by: Peter Lemenkov <lemenkov@gmail.com>