Update mods parsing code in lieu of using ModsDisplay configuration.

Closes #166 

Since linking metadata is done in html rendering layer of the ModsDisplay gem we're going to need to roll our own linking / processing logic for a few kinds of fields (most notably names and subjects).

### Names
---
![linked-names](https://cloud.githubusercontent.com/assets/96776/3167809/b533df6a-eb74-11e3-8004-15d412944ef4.png)

### Subjects
---
![linked-subjects](https://cloud.githubusercontent.com/assets/96776/3167810/bc20ad44-eb74-11e3-9630-cea5ce56d2f7.png)

### Name subjects
---
![linked-name-subjects](https://cloud.githubusercontent.com/assets/96776/3167815/c58d2a2e-eb74-11e3-8513-ec57a695f304.png)

### Email addresses
---
![linked-email](https://cloud.githubusercontent.com/assets/96776/3167816/ca88206a-eb74-11e3-9231-b8a3e92cf486.png)