Collapse #rest-api namespace into #repository
- Remove #rels-ext namespace

Partial resolution of: https://www.pivotaltracker.com/story/show/82075356
[maven-release-plugin] prepare release fcrepo4-client-4.0.0-beta-04
[maven-release-plugin] prepare for next development iteration
Merge remote-tracking branch 'fcrepo4-labs/master'