Get all issues of a collection endpoint

[dkastl]

#29 describes how to retreive a list of all collections, this endpoint provides access to all issues specified in the collections query.

As the data will be synced with a SMASH client, there is no need for paging or other API parameters available for Redmine's query API. Instead all issues of a collection should be returned in the format needed by SMASH to be used as form notes.

GET /smash/collections/[collection_id].json