DUI: bug tooltip position incorrect

# Preface
It's funny, but... here was bug before merging: tooltip doesn't appear at the right place during resizing LibraryView. But after merging [styling PR](https://github.com/DynamoDS/Dynamo/pull/2182) this bug dissapeared. Maybe, Styling PR fixed this problem.
All in all, what I have done is:
1) Changed coefficient, so that tooltip is closer to LibraryView;
2) Added code icon into tooltip.

# Before
![image](https://cloud.githubusercontent.com/assets/8158404/4075940/8f823fda-2eb5-11e4-8340-bc431b252578.png)
![image](https://cloud.githubusercontent.com/assets/8158404/4075944/98bb7008-2eb5-11e4-9204-e1f273cdeb4d.png)

# After
![image](https://cloud.githubusercontent.com/assets/8158404/4076663/3dd15ee4-2ebc-11e4-844b-c564ed109c64.png)

# Reviewers
@Benglin, please take a look.