Feature: Options to customize keybindings in config

[paulodiovani]

The default keybindings, especially Shift+C to clear notifications, are a but hard to type on a QWERT keyboard after using the Super key to show the notifications.

Would be great to have an option to remap the keybindings when NC is open.

[HelmicNewciv]

Would like this as well. I am very used to HJKL, vim-style bindings and it'd be convenient to not have to reach all the way over to my arrow keys to navigate my notifications.