Bugfix: Create directory if not exists, Feature addition: pastebin-based installer

Hi,

I've been looking for a way to manage my computercraft development through github, because quite honestly the whole "copy -> paste to pastebin -> delete file on in-game computer -> type in the stupid untypeable code into the computer again"  development cycle was filling me with rage.

I found your project to be the first one that reliably pulls from github. Thanks for building it! Now my workflow is so much more comfortable.  Work -> Commit -> Push -> Clone. Nearly normal!

I noticed that when you clone a repo, if the destination directory doesn't already exist, it simply creates the directory and doesn't actually download anything.

I've got that fixed, it now creates the destination directory before trying to download if the destination directory doesn't exist.

I also cooked up an installer for those of us with only pastebin access to our computercraft computers. It's set to my fork of this project, you'll want to change that for yours.