Remove default controller/test
Add mocha gem
Reinstate .gitkeep to integration
Add Need model
Add a Need presenter

This will build the JSON responses for a Need
Add NeedsController with create action for a valid need
Return an error response given invalid attributes
Remove .gitkeep from test directories
Add Organisation model
Add organisations importer & list of organisations

This came from the Maslow prototype. The list of
organisations is a dump from Whitehall for the
time being.
List all the organisations
Don't require params to be namespaced inside :need on create
Fix a Mocha deprecation warning.
Add remaining fields for Need, as per Maslow project.
Add unit tests for new model fields
Test that the organisation id is assigned
Explicitly define the _id field in the Organisation factory

FactoryGirl was overriding this so the _id field
was not being assigned.
Ensure that the organisations for a need actually exist
Change "organisations" to "organisation_ids"

This allows us to use the "organisations" key to give
more detail about each attached organisation.
Use one-sided habtm for Need/Organisation references