**Is your feature request related to a problem? Please describe.**
The Caps Lock and Fn keys are useful to some, and not others. I would greatly enjoy being able to use these keys as modifiers for something more useful to me.

**Describe the solution you'd like**
Add global shortcuts support for the cap locks and fn keys. While these keys are not useless and are not proper modifier keys, I feel that the design choice should be left to the app developer.

**Describe alternatives you've considered**
The only alternative would be to use a keypress listener/sender to 'remap' the key to something Electron supports; or substitute electron's shortcut functionality completely.

**Additional context**
Using a 3rd party keypress listener does not feel safe.
atom/common/keyboard_util.cc
case ':':
      *shifted = true;
      FALLTHROUGH;
    case ';':
      return ui::VKEY_OEM_1;
    case '+':
      *shifted = true;
      FALLTHROUGH;
    case '=':
      return ui::VKEY_OEM_PLUS;
    case '<':
      *shifted = true;
      FALLTHROUGH;
    case ',':
      return ui::VKEY_OEM_COMMA;
    case '_':
      *shifted = true;
      FALLTHROUGH;
    case '-':
      return ui::VKEY_OEM_MINUS;
    case '>':
      *shifted = true;
      FALLTHROUGH;
    case '.':
      return ui::VKEY_OEM_PERIOD;
    case '?':
      *shifted = true;
      FALLTHROUGH;
    case '/':
      return ui::VKEY_OEM_2;