Update proxy.ashx

If the url is encoded using uppercase letters or the "http" part is not in lower case then the UrlDecode branch is not invoked.

Update proxy.ashx

Fixing a bug in the previous fix.
Using case insensitive comparison rather than modifying the original url.
Merge pull request #120 from mikemsq/master

make sure string comparison before decoding encoded urls is case insensitive.