Change language to remove references to 'logging in'

This is really just pedantry, but since there is no concept of an 'account' and there is no password or authorisation or anything, it doesn't really make sense to talk about logging in and out. Alternative:

![screenshot from 2013-05-23 00 07 13](https://f.cloud.github.com/assets/597021/548010/43618470-c2d8-11e2-983e-f1cc32cdb043.png)
![screenshot from 2013-05-23 00 07 27](https://f.cloud.github.com/assets/597021/548012/46aee7c6-c2d8-11e2-8178-1adf577823e9.png)