Fix for vanishing thumbnails, when browser-zoom is active.

Hi, I discovered the problem that in some cases, the last thumbnail was invisible, when browser-zoom is active. The problem can be observed at [1]. When zooming to 90% the thumbnail disappears (e.g. in Chrome). The fix can be observed at [2]. When doing a lot of zooming, the last thumbnail may still disappear, but it is much more robust, than before the fix.

[1] ]http://www.knappi.org/galleria-error/themes/classic/classic-demo.html
[2] http://www.knappi.org/galleria-fixed/themes/classic/classic-demo.html



Due to a bug in jquery, outerwidth() returns the floor of the
actual outerwidth, if the browser is zoom to a value other than
100%. height() returns the floating point value.
This caused galleria to compute a wrong width for the 'thumbnails'
element. The container was not wide enough and the last thumbnail was
displayed in the next line, thus was effectively invisible.