introduce a new graph path bean for mapping the object graph

corresponds to the extended metadata class
of the previous implementation
alternative implementation of the abstract part of graph traversal

guided by information provided by the graph path bean
encode graph traversal and adjustment for chgrp and delete

includes parser for textual policy rule specification
add actual chgrp and delete requests that use new implementation
remove useless legacy comment
rearrange Spring beans and new graph operation request instances

introduces GraphRequestFactory,
removes separate context with only graph-rules.xml
factor out common model object processor methods
limit IceMapper lifetime
fix build issue for Blitz integration graph tests
rename requests ChgrpNew, DeleteNew to Chgrp2, Delete2
assume that the Hibernate model is accurate

see PR #2623
change new graph traversal server classes to being since 5.1.0
change new graph traversal blitz classes to being since 5.1.0
inject ACL voter into graph traversal via new graph request factory
make object permissions available to graph traversal and policy
minor graph traversal code tidy-up
add user permission matching to graph traversal rules
add processor method for getting required processing permissions
add permissions checking to generic model object processing
check that the chgrp is into a group of which the user is a member