[Feature Request] Configurable key bindings

[jleaders]

Tested in the latest Ubuntu 17.10 with the default desktop (Gnome) with the default Gnome Terminal 3.24, instead its intercepted and opens a file menu. I use ZSH but I doubt that's related.

I suggest we change the hotkey for Ubuntu 17.10

Also, related: typing exit and pressing enter should exit or display a text telling the user to type .exit, you know, because, UX

[joguSD]

I think we should solve this by having configurable keybindings as suggested in #202
I'll convert this into the corresponding feature request for configurable key bindings.

We can't add a message when executing exit to execute .exit for the same reason we can't make exit quit the shell. It has possible naming conflicts with the AWS service namespace so we're being defensive and requiring all shell specific commands begin with a period.