Changes toward OS-agnostic and SQL-implementation-agnostic

I have ActivateHub running on Windows! Somehow the server-side Javascript (ExecJS) inscrutable error I was getting at the hackathon went away, without my doing anything, so it's not clear Windows will just totally work. We'll see how it is moving forward.

I markdownized and included my instructions for installing the 'bluecloth' gem.

I believe the 2 code changes to not have any effect, but it would be good if someone else can review them.