FLUID-4967: Increase the distance between the UIO sliders and the right end icons

So that slider handles don't overlap on top of icons when they are at the right most end.

The issue ticket: http://issues.fluidproject.org/browse/FLUID-4967
The margin between the slider and the left end icon has been increased, by using a smaller em than the number used for the right end. Visually it produces the similar gap since the icon at the left is much smaller than the one at the right. 

Moreover, the smaller em prevents the whole line from stretching out, which causes the input field at the far right to be wrapped into the 2nd line.