Extended configurability for colors, etc

Hi Jerome

I extended the configurability of your jekyll version of the Freelancer theme. Basically all of the content can now be set from the config file. An optional amount of social network links and address lines can be set. 
The colors of the template can now also be easily configured. For this I had to rearrange the files slightly, since I had to place the css files with variables in the /_include directory for them to be built properly.

If you approve to my changes, please pull this request to your repo and feel free to add me as a contributor!

Have a nice day, 
Oliver