WIP - Custom PIO decrypt message

This replaces the default TiddlyWiki decryption message with one suitable for the PIO.

![screen shot 2014-10-21 at 14 50 13](https://cloud.githubusercontent.com/assets/958985/4722043/1fdcdaf2-593d-11e4-98f7-8bfc519c450c.png)

To do:
* [ ] Fix bug where the in-app PIO does not recognise it has been saved, causing the unsaved-changes module to wrongly warn when quitting.