installed zabbix-cli for zabbix_get

zabbix/Dockerfile

     dpkg -i /tmp/zabbix.deb
 
 RUN apt-get update && apt-get -y install\
-        zabbix-server-pgsql\
+        zabbix-server-pgsql zabbix-cli\
         snmp &&\
         apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*