Fedora objects can be any type of LDP container

Objects may also choose not to be any formal type of LDP container, and just
have ldp:contains properties to its children.
Make inbound-references an opt-in preference
Merge pull request #594 from fcrepo4/ldp-containers

Support all LDP container types
Merge pull request #597 from fcrepo4/inbound-opt-in

Make inbound-references an opt-in preference
Refactor triple generation to produce aesthetically pleasing graphs
Enforced the FedoraFileSystemConnector to be read-only.
Use methods on FedoraResource instead of getting the JCR Node
Fix versioning check when reverting versions of non-RDF resources

Resolves: https://www.pivotaltracker.com/story/show/81615202
Merge pull request #602 from lsitu/feature/readonly-connector

Enforced the FedoraFileSystemConnector to be read-only.
Merge pull request #598 from fcrepo4/better-output

Refactor triple generation to produce aesthetically pleasing graphs
Merge pull request #604 from fcrepo4/no-jcr-node

Use methods on FedoraResource instead of getting the JCR Node
refactor getClusterExecutor into Function subclass
push rarely-used repositoryService injection down inheritance tree
refactor Service into a genric interface
ignore checkstyle dot files
style conformance in UUIDPidMinter
remove unused RDF type constants and regularize produced serializations