Add user input waits before homing and loadcell zero

[tkevinbest]

🚀 Feature Request

Right now, the osl.home() routine starts moving the joints right away. I think we should require a button press before this happens for safety. Same thing for the loadcell zeroing. If you don't know it is about to happen, you might not be ready for it.

The solution is pretty simple:
input('\nPress enter to begin homing:')