I'm writing a google go package for abstracting the pure zabbix
APIs and exposing nice-to-use native data structures. The
encoding/json package included with the languge, take care
of converting a JSON to a native and ready to use structure
or array of structures.

It appear that the history.get API, for numeric values, always
return a JSON string in the value field. While it's possible to
convert the value without problems, it can be problematic for
softwares that rely on the proper JSON notation for number types
for infering the proper type for a variable, thus complicating
the implementation of programs that use the API in strongly
statically typed languages.

Steps to reproduce:
Make a simple call to the history.get API for a numeric type (integers or floats) and check the returned JSON format.

Result:

{
  "jsonrpc": "2.0",
  "result": [
    {
      "itemid": 23314,
      *"value": "0"*,
      "clock": 1516284994,
      "ns": 283022645,
      "ttl": 604800
    }
  ],
  "id": 1
}

Expected:

{
  "jsonrpc": "2.0",
  "result": [
    {
      "itemid": 23314,
      *"value": 0*,
      "clock": 1516284994,
      "ns": 283022645,
      "ttl": 604800
    }
  ],
  "id": 1
}