iOS Mobile Configuration Profile

PR to #258 - Example implementation to provide a iOS mobile configuration profile. `setup/mobileconfig.sh` generates a .mobileconfig at the default www location named `mailinabox.mobileconfig`. 

![img_2101](https://cloud.githubusercontent.com/assets/677964/4922075/1d7e1a7c-650f-11e4-8e52-b0f0d3691afc.PNG)

Username/Password prompt for each IMAP/CalDav/CardDav account

![img_2103](https://cloud.githubusercontent.com/assets/677964/4922101/4b3f5f98-650f-11e4-8c94-a831e3457a0e.PNG)
![img_2104](https://cloud.githubusercontent.com/assets/677964/4922105/4cdbf730-650f-11e4-9f33-f428644a7f41.PNG)

Mail Instructions page

![bildschirmfoto 2014-11-05 um 18 39 29](https://cloud.githubusercontent.com/assets/677964/4922571/352b5906-6513-11e4-9e83-2c387551ddf4.png)