Finsihed setting up test for first_name being set before saving user.

Made the test fail.
modified:   test/models/user_test.rb
+    # See if user object doesn't have any errors on the user's first_name.
+    assert !user.errors[:first_name].empty?

$ruby -Itest test/models/user_test.rb
> FAIL

Made the test pass.
modified:   app/models/user.rb
+  # Presence Validation
+  validates :first_name, presence: true

$ruby -Itest test/models/user_test.rb
> PASS