Test nested registered udts

Here are the datatypes that are created:
```
CREATE TYPE depth_0 (age int, name text)
CREATE TYPE depth_1 (value depth_0)
CREATE TYPE depth_2 (value depth_1)
CREATE TYPE depth_3 (value depth_2)
CREATE TYPE depth_4 (value depth_3)
```

The first line gets written, the second line is result[0]:
```
depth_0(age=42, name='Bob')
{u'v_0': depth_0(age=42, name=u'Bob')}
```

This is the value that throws the exception:
```
depth_1(value=depth_0(age=42, name='Bob'))
```

```
Traceback (most recent call last):
  File "/Users/joaquin/repos/python-driver/tests/integration/standard/test_udts.py", line 303, in test_nested_registered_udts
    s.execute("INSERT INTO mytable (k, v_%s) VALUES (0, %s)", (i, udt))
  File "/Users/joaquin/repos/python-driver/cassandra/cluster.py", line 1255, in execute
    result = future.result(timeout)
  File "/Users/joaquin/repos/python-driver/cassandra/cluster.py", line 2714, in result
    raise self._final_exception
SyntaxException: <ErrorMessage code=2000 [Syntax error in CQL query] message="line 1:70 no viable alternative at input '='">
```