Add new TransformPromoteTableEmpty
This is a new transform which promotes (table empty) operator as high up the algebra tree as possible
to minimize unecessary work that the query engine may otherwise carry out.  Currently this is not
wired into the default optimizer

git-svn-id: https://svn.apache.org/repos/asf/jena/trunk@1516656 13f79535-47bb-0310-9956-ffa450edef68