Regarding RM #3316 Pgadmin4 No Tray Crash

Hi Hackers,

I have implemented the fix for RM #3316 "Pgadmin4 No Tray Crash". I have
implemented it as follows:

- Check the availability of System Tray for 30 seconds (no changes made
here).
- If System Tray not found create one Floating Window with menu. (Refer
attached screenshot).
- I have remove close(x) button of the floating window.
- Fedora have "Quit" menu for the applications, so I have handle the
close event and shutdown the python server.

I have tested this on Fedora-28 (no system tray) and Ubuntu 18.04 (with
system tray).

Please review the screenshot and suggest changes (if any). I'll send the
patch later.

--
*Akshay Joshi*

*Sr. Software Architect *

*Phone: +91 20-3058-9517Mobile: +91 976-788-8246*