HTTP api docs: incorrect format and examples of dates of recordings

OS: OS X
Kapacitor: 1.0.0
pre-built package

As written in docs, dates of recordings('start', 'stop') are RFC3339Nano formatted. However, the server-side actually accept an ISOString.

For example, the incorrect parameters:

``` json
{
"task" : "TASK_ID",
"stop" : "2006-01-02T15:04:05Z07:00"
}
```

Will get an error: `"parsing time \"\"2006-01-02T15:04:05Z07:00\"\" as \"\"2006-01-02T15:04:05Z07:00\"\": cannot parse \"07:00\"\" as \"\"\""`

And with the correct parameters:

``` json
{
"task" : "TASK_ID",
"stop" : "2006-01-02T15:04:05Z"
}
```

Successfully submit to the server.

Start by locating the HTTP API documentation for recording requests and the examples using the `start` and `stop` parameters. Update the documented date format and examples to match the accepted ISOString form, then verify that the request example is consistent with the reported server behavior.

Written by the indexing model from the issue text.