Added noLeaf option. Solves Issue #30.

Author: rahatarmanahmed

README.md

@@ -74,7 +74,12 @@ If you would like to add classes to a certain node, give it an array of classes
       classes: ["special", "red"]
     }]
 
-Each element without children, or leaf, is automatically given a leaf class.
+Each element without children, or leaf, is automatically given a leaf class. If you would like to force certain nodes not to be leaves (won't get leaf class and will show expand/collapse icons), set noLeaf to true in a long-form listing like so:
+
+    {
+      label: 'Coffeescript',
+      noLeaf: true
+    }
 
 You can supply a single default "on-select" function for the whole tree -- it will be called whenever a branch is selected:
 

dist/abn_tree_directive.js

@@ -198,7 +198,7 @@ module.directive 'abnTree',['$timeout',($timeout)->
         # they will be rendered like:
         # <i class="icon-plus"></i>
         #
-        if not branch.children or branch.children.length == 0 
+        if not branch.noLeaf and (not branch.children or branch.children.length == 0)
           tree_icon = attrs.iconLeaf
           branch.classes.push "leaf" if "leaf" not in branch.classes
         else