Remove unnecessary divs in Preferences UI

The extra divs were causing the margins to double.

This should align the UI style with the default Symphony style better.

Re #29
For checkboxes, render input before text

This aligns our UI with Symphony's.

Re #29
changed $_SERVER to getenv
Added notes about upgrading

Only upgrading from >= 1.3 is supported now.

Deprecating all other older versions.