Fixed issue deleting non-string tags

* Fixed issue #230

Author: jkasten2

iOS_SDK/OneSignalSDK/Source/OneSignal.m

@@ -729,7 +729,7 @@ + (void)deleteTags:(NSArray*)keys onSuccess:(OSResultSuccessBlock)successBlock o
 
     for(NSString* key in keys) {
         if (tagsToSend && tagsToSend[key]) {
-            if (![tagsToSend[key] isEqualToString:@""])
+            if (![tagsToSend[key] isEqual:@""])
                 [tagsToSend removeObjectForKey:key];
         }
         else

iOS_SDK/OneSignalSDK/UnitTests/UnitTests.m

@@ -1965,6 +1965,10 @@ - (void)testDeleteTags {
     XCTAssertNil(lastHTTPRequset[@"tags"][@"key"]);
     XCTAssertEqualObjects(lastHTTPRequset[@"tags"][@"key2"], @"value2");
     XCTAssertEqual(networkRequestCount, 2);
+    
+    
+    [OneSignal sendTags:@{@"someKey": @NO}];
+    [OneSignal deleteTag:@"someKey"];
 }
 
 - (void)testSendTagsBeforeRegisterComplete {