Add initiator to account access logs

https://www.agileplannerapp.com/boards/173808/cards/3442

an initiator would represent the user who
initiated the event for a user. useful to
find out who administers a user account.

![screen shot 2014-06-24 at 11 46 14](https://cloud.githubusercontent.com/assets/230074/3367763/2c4d1b86-fb68-11e3-9a61-61c3a15dd4ce.png)