Move explicit render of mods_metadata_sections from show_image partial...

...to automatically rendered _record_metadata_{display_type} partial.

This makes the partials rendered more in line w/ how we structure MARC records.

#### Before
---
![a](https://cloud.githubusercontent.com/assets/96776/3119267/c03b58ae-e744-11e3-965b-8514afaa60c5.png)

#### After
---
![b](https://cloud.githubusercontent.com/assets/96776/3119277/cdf93470-e744-11e3-9a68-df277de274f4.png)