title: getting history from zabbix with python api
body: <p>i have one question about getting history from zabbix with python.
  I'm only start learn python, so please don't dislike) 
  so, i have little script python, who get the host, who showing all items, and i try from this information get history for the one second, but then don't filter.</p>
  
  <pre><code>&gt;&gt;&gt; from pyzabbix import ZabbixAPI
  &gt;&gt;&gt; zapi = ZabbixAPI("http://192.168.55.128/zabbix")
  &gt;&gt;&gt; zapi.login("admin", "zabbix")
  &gt;&gt;&gt; for host in zapi.host.get(filter={'groupids': '9'}):
  ...     print host
  &gt;&gt;&gt;for item in zapi.item.get(filter={'host':'Zabbix server', 'name' : 'Processor load (5 min average per core)'}):
  ...     print item
  &gt;&gt;&gt; history = zapi.history.get({"itemid" : "23297","time_from":"2014-10-04 00:10:00", "time_till":"2014-10-04 00:10:01", "output":"extend" })
  &gt;&gt;&gt; print history
  </code></pre>
  
  <p>and after this, i have all items, and no filter time, why? help please.
  P.S. 
  what i must filter, so them return to me only the value (for the setting date)</p>
  
  <p>Thanks</p>