Gimp cheat sheet

# Goodie Pull Request

**What does your instant answer do?**
Shows keyboard and mouse shortcuts from the GIMP documentation.

**What problem does your instant answer solve (Why is it better than organic links)?**
GIMP has a complicated user interface. This gives quick information on how to perform common functions.

**What is the data source for your instant answer? (Provide a link if possible)**
http://docs.gimp.org/2.8/en/key-reference.html

**Why did you choose this data source?**
It is the official GIMP documentation.

**Are there any other alternative (better) data sources?**
Highly unlikely.

**What are some example queries that trigger this instant answer?**
`gimp cheat sheet`, `gimp shortcuts`

**Which communities will this instant answer be especially useful for? (gamers, book lovers, etc)**
GIMP users

**Is this instant answer connected to a DuckDuckHack [instant answer idea](https://duck.co/ideas)?**
No.

**Which existing instant answers will this one supercede/overlap with?**
None known.

**Are you having any problems? Do you need our help with anything?**
No.

![2014-07-12-15 49 54_1680x1050](https://cloud.githubusercontent.com/assets/7873686/3562687/6743c14a-09ff-11e4-8bb7-bdbe081dbc62.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://github.com/duckduckgo/duckduckgo-documentation/blob/master/duckduckhack/styleguides/design_styleguide.md)
[*] Tested cross-browser compatibility

    Please let us know which browsers/devices you've tested on:
    - GNU/linux
        [X] WebKit
        [X] Firefox
        [X] Opera

```