Backend: implement alerting query (#847)

* Unit tests for backend

* minor change

* Implemented querNumericItems in backend

* Added query type

* Set alerting to true

* Return TimeSeries from History

* Updated alerting feature

* Fix params marshal error

* Fix params more

* Update zabbixAPIConnector.js

* Numbers, I guess

* Params Output Type

* Output marshaling

* Unmarshal and decoder error catch

* HistoryPoint and Unmarshal fixes

* Unmarshal to History

* Revert "Update zabbixAPIConnector.js"

This reverts commit e0ffdff859b6f920893a47a709493f8076e38ef4.

* Fix unmarshaling for real

* Time range integer

* Use more zabbix.Items

* Update response_models.go

* Update zabbix_api.go

* Update models.go

* Update zabbix_api.go

* Tests

* Adding more unit tests and cleaning up additional logging

* Make history request param a pointer

* Actually store datasource in cache

* Debug logs and timings

* Handle panics gracefully

* Updated Regex filter parsing

* Removed must compile

* Clean up regex filter

src/datasource-zabbix/plugin.json

@@ -7,7 +7,7 @@
   "annotations": true,
 
   "backend": true,
-  "alerting": false,
+  "alerting": true,
   "executable": "../zabbix-plugin",
 
   "includes": [