RCv3, BfV, purge option, some link fixing, updated rev history

Oy! Writing up two, no three, new features at once, plus discovered some WADL weirdness. Anyway, please take a look. I'll also send out a PDF, which you might find easier to peruse.

Added a concept section for Cloud Bursting with RackConnect V3, added info on using loadBalancer config for RCv3, added info on user_data for BfV, addd purge arg for delete server from scaling group.
The language here seems different than the rest of the doc. Instead of "You create this template...", how about "You can create this template..." would seem better.