forkme-on-github ribbons added, user can be configure ribbon on _config....

Hello,
I integrated [Fork me on Github ribbon](https://github.com/simonwhitaker/github-fork-ribbon-css) project in this theme. User can be enable ribbon on **_config.yml** with simple `active:true` command.

There are also three options to set position of ribbon, title of ribbon and of course fork url of ribbon.

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## Explanation
__title__ can be anything,
__position__ should be following things
* top-left
* top-right
* bottom-left
* bottom-right

__url__ does not have to be github url.

### Section on _*config.yml*
![](http://storage9.static.itmages.com/i/14/0913/h_1410572808_8259772_b6acde9fa3.png "on _config.yml")

### finaly theme looks like
**default theme**  
![](http://storage8.static.itmages.com/i/14/0913/h_1410573147_9494873_81544eedab.png "fork me on-github ribbon on default theme")
**example page**  
![](http://storage6.static.itmages.com/i/14/0913/h_1410572981_7848413_60f2b03a86.png "fork me-on-github ribbon on mustafahasturk.com")


Finally thanks for this awesome theme and the others.