Spellcheck component with extendedResults parameter will now include the frequency.

URL:

```
http://solr:8080/solr/core/suggest?q=foo&spellcheck.extendedResults=true&wt=json
```

BEFORE:
```
{
   "responseHeader":{
      "status":0,
      "QTime":1
   },
   "spellcheck":{
      "suggestions":[
         "foo",
         {
            "numFound":4,
            "startOffset":0,
            "endOffset":4,
            "suggestion":[
               "foobar"
            ]
         },
         "correctlySpelled",
         false
      ]
   }
}
```
AFTER:
```
{
   "responseHeader":{
      "status":0,
      "QTime":0
   },
   "spellcheck":{
      "suggestions":[
         "foo",
         {
            "numFound":1,
            "startOffset":0,
            "endOffset":4,
            "suggestion":[
               {
                  "word":"foobar",
                  "freq":1337
               }
            ]
         },
         "correctlySpelled",
         false
      ]
   }
}
```