update cucumber and refactor some of the stories

inspired by the railscasts about cucumber. Also fix a problem with ZenTest on case sensitive platforms

features/step_definitions/signup_steps.rb

@@ -0,0 +1,17 @@
+Given /^public signups are turned (.*)$/ do |state|
+  case state 
+  when 'on'
+    SITE_CONFIG['open_signups'] = true
+  when 'off'
+    SITE_CONFIG['open_signups'] = false
+  else
+    raise "public signups should be either 'on' or 'off'"
+  end
+end
+
+When /^I submit the signup form with username "([^\"]*)", password "([^\"]*)" and confirm with "([^\"]*)"$/ do |username, password, confirm|
+  fill_in 'Desired login', :with => username
+  fill_in 'Choose password', :with => password
+  fill_in 'Confirm password', :with => confirm
+  click_button
+end