Add support for Unity's Application Indicators

[pabloh]

Add support for Ubuntu's Unity tray icons, old style gtk2 icons doesn't work anymore since Ubuntu 13.04 (even using former workarounds).

I'm not quite sure how this to be implemented but this seems to be the necessary module: http://search.cpan.org/~oesterhol/Gtk2-AppIndicator-0.15/lib/Gtk2/AppIndicator.pm .

[aperomsik]

Seems at least in saucy there is a "libgtk2-appindicator-perl" package. Without indicator support, running without the --fg flag makes it look like the script did nothing -- it's not obvious that it is running in the background, or how to make it get displayed.

[aperomsik]

Very basic indicator support on my aperomsik/msjnc:indicator_wip branch. Not robust enough for a pull request yet but thought I'd mention it. For some reason, it only works with --fg; but without --fg now it shows the main dialog, where base 2.5 just disappears without a UI trace when run without --fg.