Reset default_wait_time to correct value after test

Fixes Culerity single quote test failures

spec/capybara_spec.rb

@@ -6,10 +6,11 @@ describe Capybara do
 
   describe 'default_wait_time' do
     after do
-      Capybara.default_wait_time = 2
+      Capybara.default_wait_time = @previous_default_time
     end
 
     it "should be changeable" do
+      @previous_default_time = Capybara.default_wait_time
       Capybara.default_wait_time = 5
       Capybara.default_wait_time.should == 5
     end