Created a new Goodie: PercentOf

**What does your Instant Answer do?**

My IA give the possibility to perform calcutations with percentuals


**What problem does your Instant Answer solve (Why is it better than organic links)?**

It gives a fast response without open any calculator

**What is the data source for your Instant Answer? (Provide a link if possible)**

https://github.com/puskin94/zeroclickinfo-goodies/blob/master/lib/DDG/Goodie/PercentOf.pm

**Why did you choose this data source?**


**Are there any other alternative (better) data sources?**


**What are some example queries that trigger this Instant Answer?**

4+23% 6-78% 567/30%

**Which communities will this Instant Answer be especially useful for? (gamers, book lovers, etc)**

All the communities that must makes calculations among numbers

**Is this Instant Answer connected to a DuckDuckHack [Instant Answer idea](https://duck.co/ideas)?**

No, this is a personal idea

**Which existing Instant Answers will this one supercede/overlap with?**


**Are you having any problems? Do you need our help with anything?**


**Where did you hear about DuckDuckHack? (For first time contributors)**

From an university classmate

**What does the Instant Answer look like? (Provide a screenshot for new or updated Instant Answers)**


![screen](https://cloud.githubusercontent.com/assets/8344987/5017000/e33cdf82-6aaa-11e4-80e7-0ca2aac3ae97.jpg)



## Checklist
Please place an 'X' where appropriate.

```
[] Added metadata and attribution information (https://duck.co/duckduckhack/metadata)
[] Wrote test file and added to t/ directory (https://duck.co/duckduckhack/goodie_tests)
[] Verified that instant answer adheres to design guidelines (https://duck.co/duckduckhack/design_styleguide)
[] Verified that instant answer adheres to code styleguide (https://duck.co/duckduckhack/code_styleguide)
[] 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)
        [] Safari Mobile
        [] Google Chrome
        [] Opera

    - iOS (iPad)
        [] Safari Mobile
        [] Google Chrome
        [] Opera

    - Android
        [] Firefox
        [] Native Browser
        [] Google Chrome
        []