Support Markdown for Job descriptions - WIP 83

https://assembly.com/coderwall/wips/83



Additions:
* Support markdown for job description field and added appropriate styles for markdown styling
* Layout job listing in 2 columns for better presentation
* Enhance create/edit form for new markdown edit capabilities and enhanced form errors

`note, these screenshots were taken with the old nav bar`

**Old non-markdown listing**
![old-basic](https://cloud.githubusercontent.com/assets/197892/3881596/2c81e792-218f-11e4-8700-f7272f79daab.png)

**New non-markdown listing with 2 column layout**
![new-basic](https://cloud.githubusercontent.com/assets/197892/3881595/2c79a0be-218f-11e4-9bc8-9fd4e29aba41.png)

**New markdown formatted listing**
![new-markdown](https://cloud.githubusercontent.com/assets/197892/3881632/6a9e6d8e-218f-11e4-8e67-87b64e046f6f.png)

**Markdown listing in Applying state**
![new-markdown-applying](https://cloud.githubusercontent.com/assets/197892/3881662/b6558ba4-218f-11e4-9fae-bb0efca7f6dc.png)

**Old edit mode**
![old-edit](https://cloud.githubusercontent.com/assets/197892/3881676/d4eb387a-218f-11e4-9b78-7c9df3e44a10.png)

**New edit mode** with widened form, larger description area and tweaked horizontal Title & Type fields.
![new-edit](https://cloud.githubusercontent.com/assets/197892/3881683/ebdf60ec-218f-11e4-8cf8-94789132aa19.png)


**Old validation error display**
![old-error](https://cloud.githubusercontent.com/assets/197892/3881691/fce920da-218f-11e4-9c9b-100fe4833fef.png)

**New validation error display**
![new-error](https://cloud.githubusercontent.com/assets/197892/3881696/04cadd20-2190-11e4-8f3b-d3d652862c83.png)