Adding Lowercase.pm

**What does your instant answer do?**
It transforms any string into all lowercase.

**What problem does your instant answer solve (Why is it better than organic links)?**


**What is the data source for your instant answer? (Provide a link if possible)**
N/A

**What are some example queries that trigger this instant answer?**
*lowercase GitHub*, *lower case GitHub*

**Which communities will this instant answer be especially useful for? (gamers, book lovers, etc)**
Anyone who can't turn Caps Lock off.

**Is this instant answer connected to a DuckDuckHack [instant answer idea](https://duck.co/ideas)?**
["Converting uppercase to lowercase, and vice versa"](https://duck.co/ideas/idea/345/converting-uppercase-to-lowercase-and-vice-versa)

**Which existing instant answers will this one supercede/overlap with?**
As far as I know, none.

**Are you having any problems? Do you need our help with anything?**
Nope!

**\*\*Note:** Please attach a screenshot for new instant answer pull requests, and for pull requests which modify the look/design of existing instant answers.

![screenshot](https://cloud.githubusercontent.com/assets/5560875/3608455/11dbe0ca-0d60-11e4-8d46-3c566e36824b.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)
[X] Tested cross-browser compatibility

    Please let us know which browsers/devices you've tested on:
    - Windows 8
        [X] Google Chrome   
        [X] Firefox         
        [X] Opera           
        [X] IE 10           

    - Windows 7
        [X] Google Chrome   
        [X] Firefox         
        [X] Opera           
        [X] IE 8            
        [X] IE 9            
        [X] IE 10           

    - Windows XP
        [] IE 7            
        [] IE 8            

    - Mac OSX
        [X] Google Chrome   
        [X] Firefox         
        [X] Opera           
        [X] Safari          

    - iOS (iPhone)
        [] Safari Mobile   
        [] Google Chrome   
        [] Opera           

    - iOS (iPad)
        [] Safari Mobile   
        [] Google Chrome   
        [] Opera            

    - Android
        [X] Firefox         
        [X] Native Browser  
        [X] Google Chrome   
        [X] Opera
```

Can you add tests for the example queries?

Thanks,