Added a jobs section

Added a job section.

Items I included in the list:
+ [GitHub Jobs](https://jobs.github.com/)
+ [Authentic Jobs](http://www.authenticjobs.com/)
+ [37signals Job Board](http://jobs.37signals.com/)
+ [Smashing Jobs](http://jobs.smashingmagazine.com/)
+ [Front-end Developer Interview Questions](https://github.com/darcyclarke/Front-end-Developer-Interview-Questions)
+ [Interview This!](https://github.com/ChiperSoft/InterviewThis)