Update JSQMessagesViewController.podspec

Probably a dozen times, people have forked this lib and published to CP without updating the spec, so then their fork is attributed to me. Prevent this kind of nonsense.

Recently happened again:
https://twitter.com/jesse_squires/status/960631218072035330

JSQMessagesViewController.podspec

@@ -2,17 +2,10 @@ Pod::Spec.new do |s|
 	s.name = 'JSQMessagesViewController'
 	s.version = '7.3.5'
 	s.summary = 'An elegant messages UI library for iOS.'
-	s.homepage = 'http://jessesquires.github.io/JSQMessagesViewController'
 	s.license = 'MIT'
 	s.platform = :ios, '7.0'
 
 	s.author = 'Jesse Squires'
-	s.social_media_url = 'https://twitter.com/jesse_squires'
-
-	s.screenshots = ['https://raw.githubusercontent.com/jessesquires/JSQMessagesViewController/develop/Screenshots/screenshot0.png',
-                    'https://raw.githubusercontent.com/jessesquires/JSQMessagesViewController/develop/Screenshots/screenshot1.png',
-                    'https://raw.githubusercontent.com/jessesquires/JSQMessagesViewController/develop/Screenshots/screenshot2.png',
-                    'https://raw.githubusercontent.com/jessesquires/JSQMessagesViewController/develop/Screenshots/screenshot3.png']
 
 	s.source = { :git => 'https://github.com/jessesquires/JSQMessagesViewController.git', :tag => s.version }
 	s.source_files = 'JSQMessagesViewController/**/*.{h,m}'