Unified documentation for setup

[standage]

The TRegGA configuration has been in flux, so writing setup documentation hasn't really been feasible up to this point. However, as we converge on a distribution-ready solution we should consider how we will present unified setup/installation instructions. Some things to keep in mind.

• Rather than storing large data files in the TRegGA distribution, we can rely on scripts like xgetseq and xentret to download and process the data in an automated fashion.
• I've stored the 3kRGP metadata files (in the reads directory) as compressed files to reduce the code distribution's footprint, but these would need to be decompressed (either manually or by script/makefile) before they could be used (unless we want to simply update the code to read the gzipped data).

We need to collect these and similar setup tasks, determine how much we want to automate, and then provide unified concise instructions for doing so.