Don't reset the browser unnecessarily

The Capybara spec_helper already resets the browser after each spec, so
we only need to reset after using the driver via AppRunner.

spec/spec_helper.rb

@@ -29,10 +29,6 @@ if ENV['DEBUG']
   $webkit_browser.enable_logging
 end
 
-RSpec.configure do |config|
-  config.before { $webkit_browser.reset! }
-end
-
 require File.join(spec_dir, "spec_helper")
 
 Capybara.register_driver :reusable_webkit do |app|

spec/support/app_runner.rb

@@ -51,6 +51,7 @@ module AppRunner
   def self.included(example_group)
     example_group.class_eval do
       before { AppRunner.reset }
+      after { $webkit_browser.reset! }
     end
   end
 end