[Frontend] Share Buttons

Hi guys,

These are the changes I made so far... I've shown a screenshot here: https://f.cloud.github.com/assets/293241/457838/e6c45946-b3b8-11e2-851b-fb300a7b35d5.png

I added this small share buttons and put them to work with some javascript. Changed some small things - the edit/delete buttons for the job poster, and the apply buttons (but the apply with linkeding is not functional yet, we need to see how to change the default linkedin button).

I added a table-stripped on the main listing for better readability and also added an INSTALL file with the instructions I used here for my Ubuntu, may be useful for someone... But I guess we should add the default vagrant instructions too.