FLUID-5457, FLUID-5469: Remove FSS

Removed FSS. The fss directory in the prefs framework is still there and will be addressed by [FLUID-5482](http://issues.fluidproject.org/browse/FLUID-5482)
http://issues.fluidproject.org/browse/FLUID-5469

Also adds a fix for FLUID-5457, which allows for the cross to appear when using a custom default theme.
http://issues.fluidproject.org/browse/FLUID-5457
There were some typical patterns skipped to specifically isolate the keyboard a11y stuff and make it more visible. This change sort of falls in there, but could be modified. Although I'm not exactly sure what you'd like to be changed. The onSelect is an option of the keyboard a11y plugin.