duplicate pandu-rao's doc fixes in the readme
Fixed a bug when NetworkTopologyStrategy is used.

Although the Cassandra documentation implies that the
`replication_factor` parameter would be ignored in this case its
presence will cause an error when creating a keyspace using
NetworkTopologyStrategy.
Merge remote-tracking branch 'upstream/master'
Added guards to handle None value in Date and DateTime column to_python conversion
Added guard to handle None value in Date column to_database conversion
Add testcases for guards for None in date, datetime conversion
Fixed bug in test case and expanded test case to include values_list
beginning queryset refactor with some basic statement and operator classes and a bunch of empty test files
adding where clause rendering
adding field listification
adding select field rendering
adding more select rendering and beginning dml statements
moving where rendering into it's own property
fixing str tests
adding tests around misc select statement rendering
fixing statement tests
adding a set clause
adding assignment statement base class
setting up constructors for other statements
adding deterministic context ids