Use defaults for existing environment vars

If we provide defaults for the variables the spec can be more easily run
Tests now pass when just running ./script/test
Fixed incorrect example usage of update_user()

Also would recommend that the the :bio option not be shown as this is a essentially deprecated feature.  Its not shown on GitHub.com UI and has been mentioned to be deprecated: https://github.com/github/github-services/issues/503#issuecomment-12654988
Implement detailed git commit method
Merge pull request #387 from StephenOTT/patch-4

Fixed incorrect example usage of update_user()
Merge branch 'git-commit'
Merge pull request #378 from sigmavirus24/feature-use-defaults

Feature: Use defaults for environment variables