Adds 'Find it' link to availability

![image](https://cloud.githubusercontent.com/assets/302258/3859479/0f92250c-1f19-11e4-8f2f-9297a2265e68.png)
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![image](https://cloud.githubusercontent.com/assets/302258/3859495/488ee17e-1f19-11e4-82d1-e66f126a8878.png)
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![image](https://cloud.githubusercontent.com/assets/302258/3860817/0cc6a5f0-1f28-11e4-9932-518160399f11.png)
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![image](https://cloud.githubusercontent.com/assets/302258/3860497/e58e535a-1f24-11e4-86aa-b9e97b1225e8.png)
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- [x] Add tests
@jchristo4 it looks like you've created a column for the stackmap link here but then you put the stackmap link in the location cell.  Perhaps this is leftover from moving the Find it link from item to location level.  It's causing some odd display issues in the table.

![availability-markup](https://cloud.githubusercontent.com/assets/96776/3896294/8ad5a668-2256-11e4-9c62-86c770cbd6cf.png)

![availability-display](https://cloud.githubusercontent.com/assets/96776/3896297/913ad488-2256-11e4-88a2-01c435d83349.png)