lock sinatra to version 1.3.5
Merge pull request #503 from amdprophet/lock_sinatra_version

Lock sinatra to version 1.3.5
[api] fixed aggregate issued data type, string -> int
[api] GET /stashes returns an array of stashes, drop POST /stashes for multi-get
      - added pagination
[api] updated api spec for latest changes
[api] some pagination standardization
[api] paginate clients
[apt] POST /stashes w/ path & content, check request produces a 202
[api] must provide both path & content for POST /stashes, adjusted tests
[api] must provide subscribers for a check request
Merge pull request #506 from portertech/api

GET & POST /stashes, pagination, aggregate issued data type
[api] mention stashes api change in changelog
Merge pull request #507 from portertech/api

Updated the CHANGELOG, mentioned changes to /stashes