MessagesList: Add support for beforeMessageGUID and beforeDate

kordophone/Bridge/Operations/Utilities/MBIMHTTPUtilities.m

@@ -47,3 +47,31 @@ NSString* MBIMWebServerFormatISO8601(NSDate *date)
     
     return string;
 }
+
+@implementation NSDate (MBIMWebServerFormat)
+
+- (NSString *)RFC822StringValue
+{
+    return MBIMWebServerFormatRFC822(self);
+}
+
+- (NSString *)ISO8601StringValue
+{
+    return MBIMWebServerFormatISO8601(self);
+}
+
+@end
+
+@implementation NSString (MBIMWebServerFormat)
+
+- (NSDate *)RFC822Date
+{
+    return [_dateFormatterRFC822 dateFromString:self];
+}
+
+- (NSDate *)ISO8601Date
+{
+    return [_dateFormatterISO8601 dateFromString:self];
+}
+
+@end