[Issue #465] Instead of enforcing non-nil parameter, allow it to signify not appending a path to the base URL when matching

AFNetworking/AFHTTPClient.h

@@ -300,7 +300,7 @@ typedef enum {
  Cancels all operations in the HTTP client's operation queue whose URLs match the specified HTTP method and path.
  
  @param method The HTTP method to match for the cancelled requests, such as `GET`, `POST`, `PUT`, or `DELETE`. If `nil`, all request operations with URLs matching the path will be cancelled. 
- @param path The path appended to the HTTP client base URL to match against the cancelled requests. This parameter must not be `nil`.
+ @param path The path appended to the HTTP client base URL to match against the cancelled requests. If `nil`, no path will be appended to the base URL.
  
  @discussion This method only cancels `AFHTTPRequestOperations` whose request URL matches the HTTP client base URL with the path appended. For complete control over the lifecycle of enqueued operations, you can access the `operationQueue` property directly, which allows you to, for instance, cancel operations filtered by a predicate, or simply use `-cancelAllRequests`. Note that the operation queue may include non-HTTP operations, so be sure to check the type before attempting to directly introspect an operation's `request` property.
  */

AFNetworking/AFHTTPClient.m

@@ -527,9 +527,7 @@ static void AFNetworkReachabilityReleaseCallback(const void *info) {}
 
 - (void)cancelAllHTTPOperationsWithMethod:(NSString *)method
                                      path:(NSString *)path
-{
-    NSCParameterAssert(path);
-    
+{    
     NSString *URLStringToMatched = [[[self requestWithMethod:(method ?: @"GET") path:path parameters:nil] URL] absoluteString];
     
     for (NSOperation *operation in [self.operationQueue operations]) {