Update env_vars README.md

Adds instructions for using environmental variables in a Rails console via the .bash_profile.
Update env_vars README.md

Adds instructions for using environmental variables in a Rails console via the .bash_profile and discusses alternative solutions.
Update env_vars README.md

Fixed spelling error.
Merge pull request #170 from paulasaurus/env_vars_readme

Update env_vars README.md
Merge branch 'master' of https://github.com/engineyard/ey-cloud-recipes

# By Paul Tingle
# Via Dennis J. Bell (1) and Paul Tingle (1)
* 'master' of https://github.com/engineyard/ey-cloud-recipes:
  Update env_vars README.md
  Update env_vars README.md
  Update env_vars README.md