#195

Updates to the Lunch Money Developer API:
GET /v1/categories and GET /v1/categories/:category_id now return order
.
New option for GET /v1/categories: format
. It can either flattened
 or nested
. If flattened
, returns a singular array of categories, ordered alphabetically. If nested
, returns top-level categories (either category groups or categories not part of a category group) in an array. Subcategories are nested within the category group under the property children
.)