Avoid moving retry to next host when request ID == 0

Fixes PYTHON-88
Add UserType.as_cql_query, unit test coverage
Set fetch_size correctly in Statement.__init__
Merge pull request #151 from chronology/fetch_size

Set fetch_size correctly in Statement.__init__
Fix disabling paging on a per-statement basis

Relates to #151
Fixes PYTHON-93
Add a few extra tests for tuples
Added datatype_utils file
Minor tuple test adjustments
Merge branch 'tuple-test-merge'
Fix typo in getting started guide

Fixes #154
Docs and example for Cluster.register_user_type
Update API doc methods
Friendlier exception when user type does not exist
Add comments for recently submitted tests