Newint instant answer

**What does your instant answer do?**
It displays New Internationalist magazine covers, and allows you to also add search terms to narrow the list of covers.

**What problem does your instant answer solve (Why is it better than organic links)?**
It instantly shows a list of the most recent cover images and titles so you can visually navigate to the latest edition of New Internationalist magazine.

**What is the data source for your instant answer? (Provide a link if possible)**
https://digital.newint.com.au/issues.json

**Why did you choose this data source?**
It was the best choice to work with.

**Are there any other alternative (better) data sources?**
No.

**What are some example queries that trigger this instant answer?**
newint
newint feminism

**Which communities will this instant answer be especially useful for? (gamers, book lovers, etc)**
Magazine readers, researchers & editors.

**Is this instant answer connected to a DuckDuckHack [instant answer idea](https://duck.co/ideas)?**
https://duck.co/ideas/idea/4403/new-internationalist-magazine

**Which existing instant answers will this one supersede/overlap with?**
n/a

**Are you having any problems? Do you need our help with anything?**
I wanted to have the 'editors_letter_html' render in the detail section, but couldn't figure out how to set that up.

**\*\*Note:** Please attach a screenshot for new instant answer pull requests, and for pull requests which modify the look/design of existing instant answers.

![Screen shot using trigger 'newint'](https://cloud.githubusercontent.com/assets/314298/4143290/216a1b68-33c8-11e4-914c-2cb93fed0993.png)

## Checklist
Please place an 'X' where appropriate.

```
[x] Added metadata and attribution information
[x] Wrote test file and added to t/ directory
[x] Verified that instant answer adheres to design guidelines (https://duck.co/duckduckhack/design_styleguide)
[x] Verified that instant answer adheres to code style guide (https://duck.co/duckduckhack/code_styleguide)
[x] Tested cross-browser compatibility

    Please let us know which browsers/devices you've tested on:
    - Windows 8
        [] Google Chrome   
        [] Firefox         
        [] Opera           
        [] IE 10           

    - Windows 7
        [] Google Chrome   
        [] Firefox         
        [] Opera           
        [] IE 8            
        [] IE 9            
        [] IE 10           

    - Windows XP
        [] IE 7            
        [] IE 8            

    - Mac OSX
        [x] Google Chrome   
        [x] Firefox         
        [] Opera           
        [x] Safari          

    - iOS (iPhone)
        [x] Safari Mobile   
        [] Google Chrome   
        [] Opera           

    - iOS (iPad)
        [x] Safari Mobile   
        [] Google Chrome   
        [] Opera            

    - Android
        [] Firefox         
        [] Native Browser  
        [] Google Chrome   
        [] Opera
```
I think it may be better if you truncate long titles using ellipsis, or otherwise the tiles will have different heights, as in your screenshot.