Don't install from untested raspberry-pi repo

We only want released firmware in our image.
Add working directories to .gitignore
Don't install copy of Oracle license

We're not installing Oracle Java in our images, so there's no need to
add the license.
Set hostname to localhost.

This is necessary to enable setting the hostname from dhcp.
Don't add startx notice to motd

Our image won't have X, so this is unnecessary
Reduce stage3 package list.

Removing packages that aren't needed for a minimal install.
Don't create noobs init script.

We're not going to be using NOOBS