Creation of the serializer (convert an object in whatever you want)

Issue #56 

In thread.py : 
```python
 myHost = webservices.Full()
 myHost.host = Checks.host_infos
 myHost.checks.append(check_entity)
 
 log.log_debug(objects.object_converter(myHost, "json"))
```

Return : 
```json
{
   "host":{
      "cpu_count":8,
      "uuid":"toto",
      "language":"Python",
      "kernel_version":"12.3.0",
      "hostname":"Dell-Pc",
      "cpu_model":"Intel(R) Core(TM) i7-2720QM CPU @ 2.20GHz\n",
      "os_version":"10.8.3\n",
      "os_name":"Mac OS X\n",
      "kernel_name":"Darwin",
      "architecture":"x86_64",
      "key":"toto",
      "date":"2013-03-29 15:48:45.698042",
      "model":"MacBookPro8,2\n",
      "os":"Mac OS X"
   },
   "checks":[
      {
         "date":"2013-03-29 15:48:47.001335",
         "load":{
            "last1m":"1.70",
            "last15m":"1.64",
            "uptime":84463,
            "last5m":"1.65"
         },
         "disks":{
            "disks":[
               {
                  "used":87758880768.0,
                  "name":"Mac\n",
                  "date":"2013-03-29 15:48:46.799442",
                  "size":119174365184.0,
                  "free":31153340416.0,
                  "unix_name":"/dev/disk1s2"
               },
               {
                  "used":290056925184.0,
                  "name":"Mac DATA\n",
                  "date":"2013-03-29 15:48:47.001213",
                  "size":749812400128.0,
                  "free":459755474944.0,
                  "unix_name":"/dev/disk0s2"
               }
            ]
         },
         "cpu":{
            "idle":"90",
            "system":"4",
            "user":"6"
         },
         "memory":{
            "swap_used":0.0,
            "swap_free":0,
            "resident":1376833536.0,
            "free":125407232.0,
            "inactive":3424808960.0,
            "swap_size":8579194880.0,
            "active":3652145152.0,
            "total":8579194880.0
         }
      }
   ]
}
```