title: Keen-io: i can't delete special event using extraction query filter
body: <p>using extraction query (which used url decoded for reading):</p>
  
  <blockquote>
    <p><a href="https://api.keen.io/3.0/projects/xxx/queries/extraction?api_key=xxxx&amp;event_collection=dispatched-orders&amp;filters=[" rel="nofollow">https://api.keen.io/3.0/projects/xxx/queries/extraction?api_key=xxxx&amp;event_collection=dispatched-orders&amp;filters=[</a>{"property_name":"features.tradeId","operator":"eq","property_value":8581}]&amp;timezone=28800</p>
  </blockquote>
  
  <p>return </p>
  
  <pre><code>{
      result: [
        {
            mobile:  "13185716746",
            keen  :  {
                         timestamp: "2015-02-10T07:10:07.816Z",
                         created_at: "2015-02-10T07:10:08.725Z",
                         id: "54d9aed03bc6964a7d311f9e"
                     },
            data  :  {
                        itemId: 2130,
                        num: 1
                     },
            features: {
                        communityId: 2000,
                       dispatcherId: 39,
                            tradeId: 8581
                      }
        }
     ]
  }
  </code></pre>
  
  <p>but if i use the same filters in my delete query url (which used url decoded for reading):</p>
  
  <blockquote>
    <p><a href="https://api.keen.io/3.0/projects/xxxxx/events/dispatched-orders?api_key=xxxxxx&amp;filters=[" rel="nofollow">https://api.keen.io/3.0/projects/xxxxx/events/dispatched-orders?api_key=xxxxxx&amp;filters=[</a>{"property_name":"features.tradeId","operator":"eq","property_value":8581}]&amp;timezone=28800</p>
  </blockquote>
  
  <p>return </p>
  
  <pre><code>{
      properties: {
         data.num: "num",
         keen.created_at: "datetime",
         mobile: "string",
         keen.id: "string",
         features.communityId: "num",
         features.dispatcherId: "num",
         keen.timestamp: "datetime",
         features.tradeId: "num",
         data.itemId: "num"
      }
  }
  </code></pre>
  
  <p>plz help me ...</p>