apt-get upgrade during Docker build.
Merge pull request #170 from astopy/master

apt-get upgrade during Docker build.
add indexes to HABTM joing table
remove extra index on user seen subjects

use [ user_id, workflow_id ] index for user_id instead of three index definitions
Merge pull request #171 from camallen/indexes

Index review
Add UserEnqueuedSubjects denormalization

Add after_create and after_save callbacks to Classification
model to manage denormalization
Add queued sort to subjects controller
Refactor classifications model

Use better boolean method naming, remove state enum
Remove UserEnqueuedSubject model when no more subject_ids
Add SubjectSelector class
Update for strong params configuration change
Fix counting error
Initial Work towards a better subject queue
Rename UserEnqueuedSubject to UserSubjectQueue
Add Classification Lifecycle Object and Specs
Fix subject controller tests
Partial Controller for Subject Queue
Create Fake SetMemberSubject Relation for SubjectQueue
Accept Subject Model instead of just id
Update Classification Lifecycle for new method parameters