Take control of URL encoding from embedly

Encode the URL properly before sending to embedly:

- (NSString *)encodeURLString:(NSString *)urlString
{
    return (NSString *) CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(NULL, (CFStringRef)urlString,
                                                                NULL, (CFStringRef)@";/?:@&=$+{}<>,",
                                                                CFStringConvertNSStringEncodingToEncoding(NSASCIIStringEncoding)));
}