Fix compile statement return object.

Results should not have a "status" field. It leads to return objects such as:
```
{
  "result" : {
               "kind" : "std exception",
               "msg" : "Cannot allocate memory",
               "status" : "error"
             },
  "status":"ok"
}
```
This PR fixes it so that we end up with:
```
{
  "result" : "Cannot allocate memory",
  "status" : "error"
}
```
I think it is better to let it fly by here because, for example, if we wanted to make a Better web ui for compile errors, which did things like "Highlight the expression which caused the error" you need the pos rage as a seperate thing (You could try parsing apart the error message on the client side, but why not just send the data in a more machine-friendly form?).

The std::exception one definitely should go away as it doesn't add / change anything, just makes us build yet another stringstream.