Change the expiration behavior of sessionToken

See https://bugzilla.mozilla.org/show_bug.cgi?id=1022678

 - [ ] Store the last usage and the date of activation of a sessionToken
 - [x] Automatically prune ONE_DAY old not validated sessionToken
 - [ ] As soon as a sessionToken is validated store it in a long live storage
 - [ ] cleanSession should remove both redis and longStorage keys.

We will use redis for the validation flow and as soon as the MSISDN is validated, drop validation data and build a longlive database entry to store MSISDN, creation date and last update date
Well the problem is that you need to know about their arguments in order to call them. We can improve that later but for now expicite is fine.