Add keyboard short cuts

[brysonbw]

Add the following keyboard shortcuts:

Shortcut	Action
SPACE	Start or Stop the timer
ALT + P	Pomodoro
ALT + S	Short Break
ALT + L	Long Break
ALT + R	Reset Timer

[Dhruv-Rankoti]

Hi,
I’d like to work on this issue. I’ve gone through the code and I think I can implement a fix. Could you please assign it to me?

[brysonbw]

@Dhruv-Rankoti thanks for picking up this issue. I did have something local but didn't push to remote but all smooth you can have this issue

[brysonbw]

@Dhruv-Rankoti Thanks!