Moved the Controllers to the Left

This should improve experience and usability.
The controls on the left are prone to errors, in daily usage most users use the files tabs more than they use the extension controllers, this should not fill usable space and should have a different aspect (no background seems just right).
Changed Tab Styles to a more "Clean" style.

I believe the square corner was distracting and outdated.
Removed the square corner and added slightly rounded (3px) corner to the top.
Should be more Clean and unobtrusive to the user.
Merge pull request #35 from apintocr/master

Moved the Controllers to the Left