In valkyrie/fedora ID are not in a pair tree

[dlpierce]

Descriptive summary

In valkyrie/fedora ID are not in a pair tree like http://localhost:8081/fcrepo/rest/development/21/92/c0/41/2192c041-f600-4ab2-8027-bd6b568229ec

Actual behavior (include screenshots if available)

In Valkyrie/Fedora (Sirenia) object URIs are like http://fcrepo:8080/fcrepo/rest/development/2192c041-f600-4ab2-8027-bd6b568229ec without pair tree organization

Acceptance Criteria/Expected Behavior

• [ ] Enable pair tree option in Fedora 6 container/documentation
• [ ] Allow pair tree in valkyrie fedora 6 adapter
• [ ] Add specs to check for pair tree use on resources, files, etc

Rationale (for feature request only)

Prevent the fedora base path root from containing every object

[cjcolvar]

When I ran into this issue with Avalon I made an override to ActiveFedora to ensure the application was still creating and assigning ids instead of letting Fedora generate the ID. It looks like Fedora has some code in place to still generate pair tree style ids but I wasn't able to figure out a way to make use of it without changing Java code and recompiling (which I didn't try). My guess is that there may still need to be a change to Fedora to expose the option but I could also be misunderstanding things since I don't know much about Java/Spring. See https://github.com/fcrepo/fcrepo/pull/1346