Allow custom session life-cycle logging

Added InMemStoreOptions.Logger so you may pass your own log.Logger that will be used for session life-cycle logging. You may use NoopLogger to disable logging such events.

Fixed runtime panic

Fixed an issue where a session was first accessed before its mutex was created, resulting in runtime panic.

This issue was fixed earlier and does not relate to v1.1.0.

Switched to new GAE API

This release switches to the new GAE API. There are no changes in non-GAE related parts.

The new GAE import is import "google.golang.org/appengine".

First tagged public release

Fully functioning, also supporting Google App Engine.

This version supports the old GAE API which has been deprecated.

The old GAE import was import "appengine".