Bug: File IO errors when running setup on new macOS install

[gromer]

I tried to setup akr on my new MBP, and kept running into File IO errors showing in the terminal. The setup process assumes these two directories are already in place:

1. ~/.ssh
2. ~/Library/LaunchAgents

If either of those directories do not exist, the scripts fail when trying to write config to them. I was able to fix this with some directory checks. If the needed directory doesn't exist, it will be created now, and file writes then work.

[gromer]

I noticed that PR #11 addresses some of this.