[Hipchat - Linux4] Add option to allow minimizing (closing) to tray

Love the new linux app, but it is inconvenient for me because it doesn't minimize to tray. I was informed this was expected behavior here: https://support.atlassian.com/servicedesk/customer/portal/32/HCP-8268.

The old app/client minimized to system tray, all other apps for chat Skype/Pidgin/Slack/Empathy all minimize to system tray. I would really like this feature to be added as an option if this is not default behavior because having it not minimize to system tray is very inconvenient. On Windows 10, the client also minimizes to system tray, so it seems like this is normal behavior.

Video of problem: https://vid.me/17m7

Doesn't work on
Ubuntu 15.10
Ubuntu 16.04
Ubuntu Gnome 15.10
Ubuntu Gnome 16.04
Xubuntu 15.10
Xubuntu 16.04
Linux Mint 17 MATE
Linux Mint 17.3
and on some other distro's listed in the comments (not tested by me)

Work Around
Work around that atleast makes HipChat usable:
Use http://meetfranz.com/

Features
1. Minimizes/closes to tray!
2. Just uses the regular notifications/popups via lib-notify instead of the new HipChat ones