Use new API methods to request location

Fixes #2479
Dropped unnecessary return
Merge pull request #2481 from wordpress-mobile/issue/2479-new-location-request

Use new API methods to request location
Merge branch 'develop' into issue/1901-rest-posts
Use JSON for POST requests

Previously, we were using x-www-form-urlencoded which has some problems
for nested arrays.

In this particular case, an array of dictionaries would be flattened:

```
metadata = [
        {
                id = 1,
                operation = delete
        },
        {
                id = 2,
                operation = delete
        }
]
```

would turn into

```
metadata[][id]=1&metadata[][operation]=delete&metadata[][id]=2&metadata[][operation]=delete
```

Depending on the server implementation, that would turn into an array
with just the first or last object.

One could argue this is an AFNetworking bug, but since I haven't found a
solid specification defining this, sending the requests as JSON objects
feels safer.
Fix typo
Added REST support for post metadata

Currently we support geolocation only