Check whether node is Regular and then add BIEFC.

# Before
![image](https://cloud.githubusercontent.com/assets/8158404/4574684/d6c41850-4f9e-11e4-9ffd-faab818cd8f2.png)
# After
![image](https://cloud.githubusercontent.com/assets/8158404/4574672/c052f762-4f9e-11e4-8800-b2589bf93d6e.png)
# Solution
We need to add BIEFC only when our node is regular node.
# Reviewers
@Benglin,@vmoyseenko, please take a look.

Tasks on YouTrack:
[MAGN-4986](http://adsk-oss.myjetbrains.com/youtrack/issue/MAGN-4986) DUI: "Dynamo.Nodes.Search.BrowserInternalElementForClasses" appears instead of Addons TreeView node