Create a 1.3 tag to SDURLCache

SDURLCache repo is no longer maintained. The 1.2 tag is outdated and we need to be able to reference a new 1.3 tag with latest changes, so i forked the SDURLCache repo and created a new podspec pointing to it.

See this discussion for more info :

https://github.com/CocoaPods/CocoaPods/issues/1206#ref-issue-16854808