Subject toggle

Closes #265 
Closes #400 

#### Closed
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![closed](https://cloud.githubusercontent.com/assets/96776/3476627/9b67571e-0303-11e4-82cd-961357165435.png)

#### Expanded (w/ MARC TOC and Summary)
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![expanded](https://cloud.githubusercontent.com/assets/96776/3476631/a5f19fbe-0303-11e4-8c5c-244ca7558abe.png)

#### MODS Abstract
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![mods-abstract](https://cloud.githubusercontent.com/assets/96776/3476644/d35a5e32-0303-11e4-9a24-c7355ced2571.png)

See https://github.com/sul-dlss/SearchWorks/issues/278#issuecomment-47979273 regarding Included Work.