fix(tree): fix tree component, replace ng2-tree on the angular-tree-component

Closes #1690

Author: denStrigo

angular.json

@@ -34,6 +34,7 @@
               "node_modules/font-awesome/scss/font-awesome.scss",
               "node_modules/socicon/css/socicon.css",
               "node_modules/nebular-icons/scss/nebular-icons.scss",
+              "node_modules/angular-tree-component/dist/angular-tree-component.css",
               "node_modules/pace-js/templates/pace-theme-flash.tmpl.css",
               "src/app/@theme/styles/styles.scss"
             ],