Fix up KeySpace tasks to use the supplied config

Comment in the code explains the fix, YAML returns the config hash as String->Value, but when working out the settings for the KeySpace creation task, you merge it with a has that is Symbol=>Value.

This fix ensures that we always use the Symbol=>Value version (which is what the Cassandra gem wants as well).

I needed this fix to get the 0.2 version of your gem to work with Cassandra 1.1 where LocalStrategy is no longer allowed.  The other thing I had to change was to use:

```yaml
test:
  servers: "127.0.0.1:9160"
  keyspace: "myapp_test"
  strategy_class: "SimpleStrategy"
  strategy_options: { replication_factor: 1 }
  thrift:
    timeout: 3
    retries: 2
```

Since Cassandra 1.1 no longer lets you pass the replication factor in on it's own, it has to be embedded in the `strategy_options` hash...