Verify Rails 3 to 4 without ./bin works

Looks like it is good to go. Using new major release of Hatchet that fixed all sorts of compatibility issues with running interactive consoles. Split all of that code into a separate lib: https://github.com/schneems/repl_runner
Merge pull request #114 from heroku/schneems/rails4-no-bin

Verify Rails 3 to 4 without ./bin works
fix typo, thanks @will
Update rails3.rb

Support dummy postgres DATABASE_URL for jruby
Merge pull request #116 from jkrall/master

Fix DATABASE_URL bug for jruby rails apps
Instrument the buildpack
Merge pull request #117 from heroku/schneems/logplex

Instrument the buildpack
fix buildpack version
remove lxpc error messages
update changelog
update changelog
v67
extract fetcher
cache bundler so it's only downloaded once
add cdn config file
update changelog
instrument buildpack_version
fix ruby version gemfile formatting in warning
update changelog
log buildpack name