Added roles management page

Adds support for creating/editing/deleting roles.
TODO: Setting of "Product Features" when creating/editing a role
is not supported yet (will be separate patch)
Merge pull request #22 from jprovaznik/roles1

Added user roles management page
Fixed waiting for save button

When editing a role, we have to wait for "save" showed when
ajax validation is done (thanks Dave for spotting this).
Merge pull request #23 from jprovaznik/fixed_wait_for

Fixed waiting for save button
Added CheckboxTree and extended Tree to find node by name

- you can now search nodes in whole tree with find_node_by_name(),
this method returns subtree, so you can chain it:
find_node_by_name('root).find_node_by_name('some nested node')
- ChckboxTree is just a small extension of Tree class
Added product_features property into new/edit role forms
Merge pull request #26 from jprovaznik/checkbox1

checkbox tree
support for add, edit, delete local groups. included unit test
support accessing drop-down element
Merge pull request #27 from aweiteka/groups

support for local user group add/edit/delete
Use maximized fixture for navigation test
Add Management Systems {Detail,Edit} pages