Show asset classification in overview page

This patch will show a node's classification in the overview page, based on its node classifier. This helps surface information about how collins is or isnt classifying an asset. If the asset isnt classified, it will show "Unclassified". Otherwise, it links to the classifier by name. I also added the capability to define a ```displayNameAttribute``` field in the nodeclassifier config, to set an attribute to use for display purposes. If missing, we fall back to the classifier's tag.

Unclassified asset:
![screen shot 2014-04-23 at 9 33 55 am](https://cloud.githubusercontent.com/assets/130194/2778068/c06cff76-caed-11e3-93dc-19a800a58b7c.png)

Classified asset, sans ```NAME``` attribute:
![screen shot 2014-04-23 at 9 34 16 am](https://cloud.githubusercontent.com/assets/130194/2778071/c524aa1e-caed-11e3-8acd-d357ea3cbceb.png)

Classified asset, with ```NAME``` attribute set:
![screen shot 2014-04-23 at 9 49 43 am](https://cloud.githubusercontent.com/assets/130194/2778110/27e3711c-caee-11e3-8fc4-8e06b6b17b0b.png)