Set useCSS into false

Preventing weird flickering bug caused by CSS3 translate3d. Reference:
http://stackoverflow.com/questions/13101811/flexslider-really-messing-up
-my-webpage-in-chrome

Further reading:
http://stackoverflow.com/questions/15152470/chrome-rendering-issue-fixed
-position-anchor-with-ul-in-body/15203880#15203880