Jonahstanley/refactor global to world

Suggested Reviewers: @wedaly @jzoldak 
Lettuce tests have been refactored to use a common dictionary that is local to each scenario.  At the beginning/end of each scenario, the scenario_dict is absorbed and spewed respectively.
This dictionary should be used instead of hard coding constants or importing constants from other files.
So far, this is only used in order to keep access to the course name, number and org that was created and the information relating to the current logged in user.

These changes are based off of the fact that the world is designed to be monkeypatched.  Things can be added to the scenario dictionary in the given statement and then accessed through the rest of the scenario.  However, keys and values must be set in functions (that is not at the top with other constants)

This is a bit cleaner than hard coding or importing variables as it at least keeps them in one place.  Variables that are global to only one file (different CSS selectors for example) were not refactored.