Add priority to set member subject table
Remove SetMemberSubjects from Subject Controller
Add Set Member Subject Controller

Closes #268
Extract subject response to seperate method

Correct context names in subject controller spec
Fix spelling mistakes
Merge pull request #271 from edpaget/add-priority

Add priority to Set Member Subject
extract common setup and count previous resource version saves
Merge pull request #273 from camallen/less_brittle_versioning

less brittle versioning specs
add gold_standard attribute to classification

track if the classification was made by a user with an 'expert' role on the project
add project expert classifier method

use project roles scope to determine who an expert classifier is
record gold standard data in classification lifecycle
ensure add gold standard runs in transact!
spec out non-logged in user gold standard behaviour
move to enum field for expert classifier level
add expert level for marking gold standard classification
only update expert_classifier field if gold_standard
use block to setup params on the creatable resource
allow gold_standard attribute to be null
add classification schema validator to lifecycle

use a service object to validate the payload of a classification
reject invalid classification payloads