Prevent error when Connection Manager is not installed
Add desktop file

In case dmenu is configured to use only applications that contain .desktop
files, we need one for nmcli-dmenu as well, otherwise it will not be seen.
Updated nmcli_dmenu.desktop and updated README
Merge branch 'tampakrap-master'
Filter duplicate SSIDs. PEP8 fixes.
Merge branch 'Tritlo-master'
Merge branch 'master' of https://github.com/firecat53/nmcli-dmenu