Trouble-free rbenv and bundler

Setting up a sane ruby/bundler environment isn't hard, if you use the right tools.

1. Install rbenv by following the instructions at https://github.com/sstephenson/rbenv#basic-github-checkout.

2. Follow Glenn's instructions at https://gist.github.com/glv/6004197.

3. Install rbenv-binstubs:

   git clone https://github.com/ianheggie/rbenv-binstubs.git ~/.rbenv/plugins/rbenv-binstubs

4. Install ruby-build:

   git clone https://github.com/sstephenson/ruby-build.git ~/.rbenv/plugins/ruby-build

5. Restart your shell to apply the profile changes that rbenv made.

You will need to run bundle install in all of your projects, and maybe rbenv rehash if a new gem is installed. Use rbenv install <version> to install required versions of ruby.