Merge pull request #2625 from dreampiggy/project_libwebp_dependency

Update the libwebp dependency to support using 1.0 version and above

SDWebImage.podspec

@@ -59,6 +59,6 @@ Pod::Spec.new do |s|
       'USER_HEADER_SEARCH_PATHS' => '$(inherited) $(SRCROOT)/libwebp/src'
     }
     webp.dependency 'SDWebImage/Core'
-    webp.dependency 'libwebp', '~> 0.5'
+    webp.dependency 'libwebp', '>= 0.5'
   end
 end