Extracted hard-coded URLs, layer names etc and made them externally conf...

...igurable (i.e. by chef).

Lots of whitespace/formatting/commented-out-code cleanups along the way.

Sorry that the cleanup code is merged in with the functional changes - I started going down the path of separate commits, but that in itself was getting too messy.

This appears to work, but with my limited knowledge of AUV functionality, it *may* be worth getting @pmbohm to check this over when it's deployed.