Improve label node list appearance

Minor formatting changes.
* Disallow linebreak in node name or right after the icon
* Eliminate line decoration between node name and icon
* Use heading instead of plan text label and colon

Before:
![before](https://f.cloud.github.com/assets/206841/1297321/656020ca-30df-11e3-8a5c-071fe828b2eb.png)
After:
![after](https://f.cloud.github.com/assets/206841/1297324/6b3a0f60-30df-11e3-9f4c-780e8f16e043.png)