rename _validate_lazily to _validate_required_lazily
fix DocumentBase.save
use jsonobject's DecimalProperty and TimeProperty
fix ProxyDict
remove support for creating schemas as instances of DocumentSchema
remove support for using schema instance as item_type
change error message expected in test
finish fixing a test
change tests to expect validate to return None
change tests to expect adding the wrong type of element to a typed container to fail fast

raises BadValueError
change tests to expect containers to normalize their values eagerly