Use Ruby 2.0.0 and Rubygems 2.0.3

These are the defaults on Heroku now.
Remove trailing slash from PATH entry.

This is really just an aesthetic thing, but it looks odd when `which ruby`
returns '/opt/ruby/bin//ruby'
Move Postgres user creation later.

This needs to be sometime after Postgres starts. Previously it was before
Postgres started.
Merge pull request #27 from georgebrock/master

Ruby 2.0.0, and some minor fixes
Changed git clone URL to the public HTTPS one
Merge pull request #29 from pimterry/patch-1

Changed git clone URL to the public HTTPS one
Add an updated box to the 'Easy Install' instructions
Merge pull request #30 from ntodd/master

Add an updated box to the 'Easy Install' instructions
Updated to install-world to install the extensions as well
Merge pull request #35 from bjfish/master

Updated to install-world to install the extensions as well