Add a menu to Linux

[antonio-ramadas]

The app works on Linux, but the right click on top of the icon does not display the list of menus. This is a known Electron limitation.

I can see this being fixed in one of 2 ways:

1. Add a UX/UI label and think of this problem as a current bad design and iterate from there
2. Figure out a way to show the menu

The menu I am talking about is this one:

P.S.: This is particularly important because it is on this menu that the quit action is shown. Currently, Linux users do not have an easy task quitting Palbum.