Major update for Nested List

### Major update for Nested List:

* Added DoctrineORM support. NestedSet now supports DoctrineORM and Propel.
* Added insert before and insert after allowing easy drag & drop sorting.
* Added styles for Twitter Bootstrap theme.
* Added translations.

Warning! In order to make all elements sortable Nested Set list requires one fake parent element as tree root. This way all elements are in the same tree and can be ordered. For more info see: http://stackoverflow.com/questions/8769759/moving-root-or-parent-nodes-doctrine-nestedset-extension

Refs: 

* #234 Nested set for doctrine
* #237 TODO: Twitter theme

### Major general update:

* Update jQuery to 1.8.3
* Reorganize assets
* Remove old (unused) assets