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
Insert the 'check fixity' link in the HTML serialization by using the hasFixityService predicate
Merge pull request #605 from fcrepo4/check-fixity

Insert the 'check fixity' link in the HTML serialization by using the ha...
refactor getClusterExecutor into Function subclass
push rarely-used repositoryService injection down inheritance tree
refactor Service into a genric interface

simplify node existence checks in AbstractService and delete commented-out code
Checkstyle updates
ignore checkstyle dot files

style conformance in UUIDPidMinter
remove unused RDF type constants and regularize produced serializations
Merge pull request #606 from fcrepo4/80959252

Eliminate dead code

Related to: https://www.pivotaltracker.com/story/show/80959252
Remove datastream references from HTML UI controls