Specify latest redis tag.

To stop fig pulling every damn version.
Merge pull request #263 from astopy/master

Specify latest redis tag.
Return version and content_language with workflow
Reject classifications without required metadata
apt-get upgrade during docker build
Merge pull request #267 from astopy/master

apt-get upgrade during docker build
Add missing && to Dockerfile.
Merge pull request #269 from astopy/master

Add missing && to Dockerfile.
Fix Controller versioning examples
Add versioning specs to versioned controllers
Rename sort random to sort cellect

closes #257
Merge pull request #272 from edpaget/rename-random-to-cellect

Rename sort random to sort cellect
Merge pull request #265 from edpaget/add-workflow-version-to-classification

Add workflow version to classification
Merge pull request #270 from edpaget/add-versioning-spec-to-controllers

Add versioning spec to controllers