[WIP] Customize Record Metadata

Closes #67 

Still need to port the MARC tests over from the old SearchWorks codebase.

#### http://searchworks.stanford.edu/view/8501612
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![8501612](https://cloud.githubusercontent.com/assets/96776/2993691/527d5574-dcbd-11e3-924e-6dadb0d7d0d1.png)

#### http://searchworks.stanford.edu/view/4688803
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![4688803](https://cloud.githubusercontent.com/assets/96776/2993695/7a8709ca-dcbd-11e3-88cb-201fe0ab5768.png)

#### http://searchworks.stanford.edu/view/10014384
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![10014384-1](https://cloud.githubusercontent.com/assets/96776/2993697/80124616-dcbd-11e3-8ba4-fdb472042ec6.png)
![10014384-2](https://cloud.githubusercontent.com/assets/96776/2993698/82344296-dcbd-11e3-9299-e6cceb2cd46c.png)

#### http://searchworks.stanford.edu/view/7931057
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![7931057](https://cloud.githubusercontent.com/assets/96776/2993699/8bf651d4-dcbd-11e3-8a2f-88147922dd1c.png)


#### http://searchworks.stanford.edu/view/5458897
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![5458897-1](https://cloud.githubusercontent.com/assets/96776/2993702/8fa5b4a0-dcbd-11e3-9414-9d49941b5cc4.png)
![5458897-2](https://cloud.githubusercontent.com/assets/96776/2993703/92908dac-dcbd-11e3-80c5-ed23c74d990f.png)