deletedFlag implemented

can be set in model by protected $_hasDeletedFlag = true;
it is also possible to get those rows by using a ignoreDeleted in Kwf_Model_Select
usage for example:
$s = new Kwf_Model_Select();
$s->ignoreDeleted();
Merge pull request #73 from yacon/master_delete

added the possiblity of just setting a deletedFlag at deleting