Issue title: Adding data with REST api does not work. Telnet or Netcat does work
 Issue body: Hi,

I'm stumped. Submitting exactly the same data via a netcat works fine, but using the REST api doesn't.

When submitting the following Json file using the rest API, I get a good clean 204 response. 

```
{
    "name": "tim.test",
    "timestamp": 1413567971,
    "value": 18,
    "tags": {
        "host": "loadbalancer"

    }
}
```

As in:

```
Tims-MacBook-Pro:magnetic tim$ http POST http://116.69.203.115:8081/api/v1/datapoints < test/json/kairos_metric.json 
HTTP/1.1 204 No Content
Content-Type: application/json; charset=UTF-8
Server: Jetty(8.1.8.v20121106)



Tims-MacBook-Pro:magnetic tim$ 
```

However, when trying to retrieve the data, it is nowhere to be seen:

```
Tims-MacBook-Pro:magnetic tim$ http POST http://116.69.203.115:8081/api/v1/datapoints/query < test/json/kairos_metrics_get.json 
HTTP/1.1 200 OK
Access-Control-Allow-Origin: *
Cache-Control: no-cache
Content-Type: application/json; charset=UTF-8
Expires: 0
Pragma: no-cache
Server: Jetty(8.1.8.v20121106)
Transfer-Encoding: chunked

{
    "queries": [
        {
            "results": [
                {
                    "name": "tim.test", 
                    "tags": {}, 
                    "values": []
                }
            ], 
            "sample_size": 0
        }
    ]
}
```

Then, turning to plain TCP, I enter exactly the same metric:

```
Tims-MacBook-Pro:test-shop tim$ echo "put tim.test 1413567971 18 host=loadbalancer" |nc -w 30 116.69.203.115 4242 
```

Now the metric is in the DB. Great!

```
Tims-MacBook-Pro:magnetic tim$ http POST http://116.69.203.115:8081/api/v1/datapoints/query < test/json/kairos_metrics_get.json 
HTTP/1.1 200 OK
Access-Control-Allow-Origin: *
Cache-Control: no-cache
Content-Type: application/json; charset=UTF-8
Expires: 0
Pragma: no-cache
Server: Jetty(8.1.8.v20121106)
Transfer-Encoding: chunked

{
    "queries": [
        {
            "results": [
                {
                    "name": "tim.test", 
                    "tags": {
                        "host": [
                            "loadbalancer"
                        ]
                    }, 
                    "values": [
                        [
                            1413567971000, 
                            18
                        ]
                    ]
                }
            ], 
            "sample_size": 1
        }
    ]
}
```

So, I guess the Rest interface for submitting metrics is broken, or I'm missing something

 Comments: 
 Comment 0: Hi,
Your JSON is not valid, you have a typo: the metric name final quotes are missing.

Why the server returns a 204 instead of an error with an exception message is probably a bug that deserves investigation.

 Comment 1: Hi,

sorry, that's a typo specific to this github post. My source has 100% correct json. I've updated it in my initial post. But I found the "bug". I was using Unix epoch time in SECONDS not in milliseconds, as requested by KairosDB.  Strangely, the TCP method of adding datapoints converts seconds to milliseconds...that is the only thing that I can figure out to explain this. 
I now just multiply my data source's timestamps by 1000 and everything is ok. 

 Comment 2: Yes the telnet api was made to be compatible with opentsdb which only has second granularity.  The telnet api actually takes both milliseconds and seconds, it figures out which is which based on how big the number is.  I know it isn't perfect.
The rest api only takes milliseconds and you have discovered.

I think the better solution here is to split the telnet api into two end points, one that takes seconds and one that takes milliseconds.  I'll leave this open to address that issue.

 Comment 3: or just totally ignore seconds? because how do you differentiate between

1413567971 (as ms = 17.1.1970 8:39:27am UTC)  and 1413567971 (as s = 17.10.2014 5:46:11pm UTC)?

 Comment 4: @brianhks @FrEaKmAn I guess we should edit the title of this issue to something like "telnet API only takes seconds". A good solution to this would be to introduce a simple "granularity" flag which defaults to the a specific value for each endpoint, i.e: &granularity=msec

 Comment 5: I've added a "putm" telnet command that takes millisecond timestamps only.

{'source': 'GithubIssues', 'repo_name_with_owner': 'kairosdb/kairosdb', 'issue_id': 46131883, 'repo_stars': 1671.0}