fix(driver): When we give up on trying a query, callback an error.

When we give up on a query, we are returning as if the query succeeded. This fixes that.

The traceback of the crash this bug caused:
```
TypeError: Cannot call method 'rowCount' of undefined
    at checkValidResult (/opt/ele-bundle-08a28e111963e6c6386cee5f0d17e16c34bd85b9/node_modules/cassandra-orm/lib/orm/iterator.js:195:25)
    at /opt/ele-bundle-08a28e111963e6c6386cee5f0d17e16c34bd85b9/node_modules/cassandra-orm/lib/orm/iterator.js:326:25
    at /opt/ele-bundle-08a28e111963e6c6386cee5f0d17e16c34bd85b9/lib/db/utils.js:47:5
    at /opt/ele-bundle-08a28e111963e6c6386cee5f0d17e16c34bd85b9/node_modules/cassandra-client/lib/driver.js:912:5
    at finished (/opt/ele-bundle-08a28e111963e6c6386cee5f0d17e16c34bd85b9/node_modules/cassandra-client/lib/driver.js:975:7)
    at Object.whilst (/opt/ele-bundle-08a28e111963e6c6386cee5f0d17e16c34bd85b9/node_modules/async/lib/async.js:562:13)
    at /opt/ele-bundle-08a28e111963e6c6386cee5f0d17e16c34bd85b9/node_modules/async/lib/async.js:558:23
    at /opt/ele-bundle-08a28e111963e6c6386cee5f0d17e16c34bd85b9/node_modules/cassandra-client/lib/driver.js:942:17
    at wrapped (/opt/ele-bundle-08a28e111963e6c6386cee5f0d17e16c34bd85b9/node_modules/cassandra-client/lib/utils.js:29:10)
    at /opt/ele-bundle-08a28e111963e6c6386cee5f0d17e16c34bd85b9/node_modules/cassandra-client/lib/driver.js:600:7
```