Add count method to RKMappingResult

Code/ObjectMapping/RKMappingResult.h

@@ -32,5 +32,6 @@
 - (id)asObject;
 - (NSArray *)asCollection;
 - (NSError *)asError;
+- (NSUInteger)count;
 
 @end

Code/ObjectMapping/RKMappingResult.m

@@ -106,4 +106,9 @@
     return [NSString stringWithFormat:@"<%@: %p, results=%@>", NSStringFromClass([self class]), self, self.keyPathToMappedObjects];
 }
 
+- (NSUInteger)count
+{
+    return [[self asCollection] count];
+}
+
 @end