Separating content type and text encoding when constructing cached response

[mj]

While using AFCache I noticed that apparently UIWebView gets confused when the text encoding is part of the MIME type (aka content type) field of a NSURLResponse. This can happen when the original request was responded by a web application with e.g. the perfectly legal header Content-type: text/html; charset=utf-8.

I fixed this by implementing a simple parser for MIME types per RFC 2616 (see section 3.7) and using that one to split the content type and the text encoding.

Please let me know if you like the patch. If further works needs to be done to get this into your branch, I'd be happy to do that.

[kteman]

This should be added. It worked great to eliminate the problem of UIWebview showing HTML code instead of the actual webpage due to mime types not being recognized.