At the moment, using the "Remember me" function on more than one device will only work with the last device used. Previous devices will not auto login.
This PR introduces a new DataObject for storing hashed tokens against multiple devices. Developers can configure if logging out should discard all tokens, or only the one used on the device logging out; token expiry date is 90 days by default but configurable. For added security, the old behaviour can still be enforced if multiple tokens are not desired.
See silverstripe#1574 for additional background
