Fixed step definition for "Given a student with the username __ exists"

Fixed step definition for "Given a student with the username __
exists". It was implemented by manipulating the GUI to add a new user.
This should be done directly using the model code to reduce the steps
reliance on other features in the software.
Renamed step definition for Given "an assignment named "____" exists" to Given "a team assignment named "___" exists"

The step definition does far more than make sure that assignment
exists. It adds multiple team members, which is not indicated by its
name.
Added step definitions in step_definitions/authentication_steps.rb for Given "I am not logged in" and When "I log in as _ with password _".

Rewrote the Successful Login feature in the student/login.feature to check that the user is not logged in and to use the new login step with password.
I rewrote the Given /^add "(\S+)" to this "(\S+)"$/ and the Given /^a team assignment named "(\S+)" exists$/ step definitions in the features/step_definitions to manipulate data at the model level. Previously they had been using the UI to sign in as an admin and create or modify objects.

Added the And /^I edit "(\S+)" to have the name "(\S+)"$/ to the new edit_instructor.rb file in the step definitions.
Fixed the Given /^a team assignment named "(\S+)" exists$/ method. It was not setting the team_assignment or availablity_flag fields, so assignments were not working as expected.

Fixed the Given /^add "(\S+)" to this "(\S+)"$/ method. It was not saving the participant objects it created to the database. It was also not assigning a role to the participants.
Made a change to the Given /^add "(\S+)" to this "(\S+)"$/ step definition in features. It was not setting the review_allowed field to true.
Added a step that presses the "Select" button to the step definition in features/step_definitions/manage_review_steps.rb.
Merge branch 'master' into crbarile
I have added a seeds.rb file that can be used to add seeds for the cucmber tests. As of now, it creates a generic student user that is used in several of the tests.
Added step definitions to edit_instructor.rb and create_instructor.rb, and added the rewritten version of features/admin/edit_instructor.feature.

These fix the Edit an Instructor feature.
Merge pull request #233 from chrisb1609/master

CSC 517 Fall 2012 - E725 Cucumber Tests