renaming the value manager's initial_value field to previous_value
adding flags for checking if an object has been persisted and if it can be persisted with an update
adding support for either insert or update statements on object persistence
updating changelog
adding test around deleting multi key models
Implementing batch queries (not tested yet)
restructuring some of the batch query internals, putting some unit tests around batch querying
adding documentation for batch queries
adding support for partial updates for set columns
adding support for partial updates for list columns
adding support for partial updates for map columns
fixing failing unit test
adding user configurable keyspace
Merge remote-tracking branch 'upstream/master'

Conflicts:
	cqlengine/connection.py
	cqlengine/models.py
Temporary batching fixes.
fixing bug caused by batch objects on querysets being copied
updating batch query to work with 1.2
updating batch query to work with 1.2
Merge branch 'master' of github.com:bdeggleston/cqlengine
Merge remote-tracking branch 'upstream/master' into cqlengine-update

Conflicts:
	cqlengine/query.py