fab: Ensure valid_envs is always set
fab: add lots of requires

so we get a sensible error message if you forget to add
staging/production/xyz before your key command
Merge branch 'develop' of git://github.com/aptivate/dye into develop

* 'develop' of git://github.com/aptivate/dye:
  Add colon to mysql root password prompt
  Improve cookiecutter sections
  Add cookiecutter prefix to variables used in if statements
  Don't use timedelta total_seconds() method
  Fix variables missing cookiecutter. prefix
  Truncate database username to 16 characters
  correct invalid json
  Allow the django jenkins package version to be set
  Fix issue #19 with collect static.
  Import sys into local settings
  Use RedirectView CBV as default django is now 1.5
  Use _link_files for debian style apache conf
  Print the command line that failed if "pip install distribute" fails. Usually the virtualenv moved.
  cookiecutter: use the use_pytest variable in manage.py
  Revert "Remove if statements from cookiecutter stuff"
  Remove if statements from cookiecutter stuff