Added use-css-translate flag

Added the attribute use-css-transte (default: true).

There are some situatiosn where using css translate to move the inner
DIV breaks the content, I added a simple flag to use an anternative
method.

use-css-translate="true" -> translate(-offset)
use-css-translate="false" -> top: -offset
Merge pull request #4 from cosme-benito/master

Added use-css-translate flag