Add a filetree-like widget for z3views

[frapell]

Have something like the file tree browser, but, instead of folders and files, it will be a list of z3views, organized hierarchically by product name:

product.dotted.name
|
|__ view_name_1
| |_ python
| |_ template
| |_ zcml
|
|__ view_name_2
| |_ python
| |_ template
| |_ zcml
|
product.dotted.name2
|
|__ other_view
| |_ python
| |_ template
| |_ zcml
|
|__ new_view
| |_ python
| |_ template
| |_ zcml

So, if clicking on "python" you'll get the python file, if clicking in "template" you get the pt, and zcml you'll get the configure.zcml where the view is defined.