added github link in header

Added the github icon in header. 
![github_link_in_header](https://f.cloud.github.com/assets/929753/2159045/e2ecf4c4-949d-11e3-8b10-88f8df3b7d70.png)


It will be nice if make them to open in new tab/page. Will do that in next commit.

Fixes #192 

-- 
*Rajeswari*
*midnight foxes of [@spritle-dev-team](https://github.com/orgs/spritlesoftware/teams/spritle-dev-team)*