Changed 'labelhtml' to 'title' in skin design form to allow the input
labels to use the <label> tag and therefore be accessible to screen
readers.
Modified the position choosers to have hidden labels and (hopefully)
fixed cross-browser inconsistencies in the layout.
Also modified the structure of the radio pieforms element to fix issues
with screen readers.

Change-Id: I8706c34e2c2a86b0f3d54b5f0c54d337ecc251a6
Signed-off-by: Jono Mingard <jonom@catalyst.net.nz>