GET & POST /stashes, pagination, aggregate issued data type

POST /stashes to create a stash, accepting a JSON post body with a path and content.
eg. {"path": "test", "content": {"key": "value"}}

GET /stashes returns an array of stashes.
eg. [{"path": "test", "content": {"key": "value"}}]

Pagination support, limit and offset GET params, currently applied to /clients and /stashes. Default is no limit.
eg. GET /clients?limit=100&offset=100

Aggregate issued timestamps are now integers.

Check request now returns a 202, as it publishes an AMQP payload.