Watch process

So here I would make ParseArguments return an error that you would handle in the main function. You will then need a `PrintUsage()` function in this file so in the main if there is an error, you can print the error and then call `PrintUsage()`. Have a look at how args are managed in this program https://github.com/progrium/termshare/blob/master/termshare.go I think we want to make something similar