Construct existing needs from the API adapter.
View an existing need in the edit form.
Fix the representation of needs from the API.

The API uses `id` as the field name for the need ID, rather than
`need_id`.
Add a method to update a Need instance.
Save need updates with the new adapter method.
Update needs through the edit form and Need API.
Add a link to each row in the need list.
Change form title for editing a need.
Merge pull request #14 from alphagov/view-and-edit

View and edit needs