Update to SolrCoreAdmin create method incorrect action 

It currently has:

```python
        params = {
            'action': 'STATUS',
            'name': name,
            'config': config,
            'schema': schema,
        }
```

It should be:

```python
        params = {
            'action': 'CREATE',
            'name': name,
            'config': config,
            'schema': schema,
        }
```