Add method to remove a version

- Update versionRemove to also remove labels and refuse to remove the current version
- Add HTML UI for deleting versions

Resolves: https://www.pivotaltracker.com/story/show/69177560
Create new identifier translation framework with unit tests

- Deprecate GraphSubjects...
- Remove deprecated methods from GraphSubjects
- Integrate new identifier translation system into HTTP layer
- Add reverse translation to HTTP API

Resolves: https://www.pivotaltracker.com/story/show/67618364
add HTTP Link headers for describedby/describes to link a fcr:content resource to its metadata
resolve acl issue where user with reader and writer roles can't read
Merge pull request #287 from ksclarke/acl-writer-68547530

resolves issue where user with 'writer' role can't list ACL

Resolves: https://www.pivotaltracker.com/story/show/68547530
Adding Link header referencing LDP#DirectContainer (fixes https://www.pivotaltracker.com/s/projects/684825/stories/69469226)
Merge pull request #293 from futures/ldp-directcontainer

Adding Link header referencing LDP#DirectContainer

Fixes https://www.pivotaltracker.com/s/projects/684825/stories/69469226
Update LDP membership triples

Resolves: https://www.pivotaltracker.com/story/show/69469312)
Merge pull request #286 from futures/described-by

add HTTP Link headers for describedby/describes to link a fcr:content resource to its metadata

Addresses: https://www.pivotaltracker.com/story/show/69469938
Add support for OPTIONS requests on nodes with appropriate headers specified by LDP

Fixes https://www.pivotaltracker.com/story/show/69467500
Add last-modified header on content/datastream updates

Resolves: https://www.pivotaltracker.com/story/show/68301562
added file system clean-up of previous build artifacts
Merge pull request #295 from ksclarke/FedoraFileSystemConnectorIT-fs-cleanup-69013802

added file system clean-up of previous build artifacts
Implement Prefer: HTTP headers to control LDPC hierarchy serialization

Resolves: https://www.pivotaltracker.com/story/show/69467742
Updating paging headers and links (next link/header only present when there are more records)

Resolves: https://www.pivotaltracker.com/story/show/69469628
Add round-trip GET/PUT tests for objects and datastream responses
Add ldp:contains predicates for child members of an object

Fixes: https://www.pivotaltracker.com/story/show/69633558
Non-functional update

- Reduce unit and integration test logging in fcrepo-http-api
Fix reposting error handling for indirect datastream creation via FedoraNodes

Resolves: https://www.pivotaltracker.com/story/show/69610980
Update README.md

Fix README link to wiki