Add support nested groups on the Repositories page

Fix for #725.
Also covers #527.

This is a squashed commit of the following commits,
merging and closing pull request #1267:

commit 55fee41769ffab1aff59344fe117d481687aa743
Author: Martin Spielmann <mail@martinspielmann.de>
Date:   Mon Nov 6 17:19:53 2017 +0100

    declared local variable final to fix travis build

commit 131e4d14a48c2a3fdce621fa54637de50684d040
Author: Martin Spielmann <mail@martinspielmann.de>
Date:   Mon Nov 6 14:11:55 2017 +0100

    fix formatting (use tab for identation)

commit 8da5f6d5967894f157251c320928acdab3a451e7
Author: Martin Spielmann <mail@martinspielmann.de>
Date:   Mon Nov 6 13:45:39 2017 +0100

    Add repositoryListType tree. Addresses #725, 527 and includes #1224

commit 6c061651fb95212ae242dbca06c8d9ef80146201
Merge: f365daa3 40ee9653
Author: Martin Spielmann <mail@martinspielmann.de>
Date:   Sat Nov 4 13:19:08 2017 +0100

    Merge remote-tracking branch 'collapsible/ticket/527' into 725_nested_repos

commit f365daa3b1d6be135365f9b11bdece320beabf4e
Author: Martin Spielmann <mail@martinspielmann.de>
Date:   Sat Nov 4 13:10:24 2017 +0100

    first working version of tree model

1 files changed, 49 insertions, 0 deletions

diff --git a/src/test/java/com/gitblit/wicket/panels/TreeNodeModelTest.java b/src/test/java/com/gitblit/wicket/panels/TreeNodeModelTest.java
new file mode 100644
index 00000000..449688b0
--- /dev/null
+++ b/src/test/java/com/gitblit/wicket/panels/TreeNodeModelTest.java
@@ -0,0 +1,49 @@
+package com.gitblit.wicket.panels;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+
+import com.gitblit.models.RepositoryModel;
+import com.gitblit.models.TreeNodeModel;
+
+public class TreeNodeModelTest {
+
+    @Test
+    public void testContainsSubFolder() {
+        TreeNodeModel tree = new TreeNodeModel();
+        tree.add("foo").add("bar").add("baz");
+
+        assertTrue(tree.containsSubFolder("foo/bar/baz"));
+        assertTrue(tree.containsSubFolder("foo/bar"));
+        assertFalse(tree.containsSubFolder("foo/bar/blub"));
+    }
+
+    @Test
+    public void testAddInHierarchy() {
+        TreeNodeModel tree = new TreeNodeModel();
+        tree.add("foo").add("bar");
+
+        RepositoryModel model = new RepositoryModel("test","","",null);
+
+        // add model to non-existing folder. should be created automatically
+        tree.add("foo/bar/baz", model);
+        tree.add("another/non/existing/folder", model);
+
+        assertTrue(tree.containsSubFolder("foo/bar/baz"));
+        assertTrue(tree.containsSubFolder("another/non/existing/folder"));
+    }
+
+    @Test
+    public void testGetDepth() {
+        TreeNodeModel tree = new TreeNodeModel();
+        TreeNodeModel bar = tree.add("foo").add("bar").add("baz");
+
+        assertEquals(0, tree.getDepth());
+        assertEquals(3, bar.getDepth());
+    }
+
+
+}