Token function
do not call count() in QuerySet.__len__
QuerySet.values_list support
memory leak fix
Merge remote branch 'upstream/master'
Merge branch 'master' of git://github.com/bdeggleston/cqlengine
Merge remote branch 'upstream/master'
changed .all() behaviour - it clones QuerySet as in Django ORM
clustering order, composite partition keys, Token func, docs & tests
merge

Conflicts:
	cqlengine/query.py
Merge branch 'master' of git://github.com/bdeggleston/cqlengine
Fix for #41
Merge branch 'master' of github.com:mrk-its/cqlengine into pull-40
adding some docstrings to the function classes
removed unused column class
adding some docstrings and comments
adding some todos
adding cassandra docs url to token function docs
removing commented out method
adding contributor guidelines