TreeView - Shouldn't allow click on empty non-leaf nodes

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.0.3
• Fix Version/s: 1.0.x
• Component/s: Tree
• Labels: None
• Git Pull Request: https://github.com/natecavanaugh/alloy-ui/pull/163

In the TreeView component, empty non-leaf nodes can be clicked to the left causing a strange toggling behavior.

Steps:
1. Open the index.html example on TreeView on Alloy
2. Click to the left of the node CheckboxNode, where the arrow is meant to be

Result:
The node initiates a loading process

Expected:
Nothing to happen