Need a right-click popup menu

[geekytime]

It looks like we'll have to roll our own right-click context menus.

This menu example shows how to use the electron menus from within the browser via remote.

[geekytime]

The bare minimum we'd need would be copy/paste I guess, but a full "edit" menu would be good eventually.

[LongLiveCHIEF]

Mattermost also has some pretty slick keybindings, and I think it would be great to list the keybindings in the context menu's to help user's learn the keybindings.