Remove Twitter URL until CocoaPods fixes their handling.

Alamofire.podspec

@@ -4,7 +4,6 @@ Pod::Spec.new do |s|
   s.license = 'MIT'
   s.summary = 'Elegant HTTP Networking in Swift'
   s.homepage = 'https://github.com/Alamofire/Alamofire'
-  s.social_media_url = 'http://twitter.com/AlamofireSF'
   s.authors = { 'Alamofire Software Foundation' => 'info@alamofire.org' }
   s.source = { :git => 'https://github.com/Alamofire/Alamofire.git', :tag => s.version }
   s.documentation_url = 'https://alamofire.github.io/Alamofire/'