tree-control
https://github.com/wix/angular-tree-control
https://github.com/wix/angular-tree-control/issues/274
modded w/ promise & server side - http://embed.plnkr.co/CcRiGi/ by BccSafe
bootstrap-nav-tree
https://c9.io/greentest/angular-bootstrap-nav-tree
https://github.com/nickperkinslondon/angular-bootstrap-nav-tree