Update examples to use leaflet 0.7.1
Remove vendor prefixes on border-radius

They're no longer needed, acccording to canIuse.com. Still keeping
webkit-transform since webkit for some reason still wants a prefix.
Remove superflous CSS rules

They're covered by default CSS values anyway.
Remove bg-pos as it is no longer needed
Fix #49, ensure border radius is less than border

When the radius is less than the border, the inside will have square
corners, which eliminates our problem. Also made sure that the icon only
has one rounded corner, and only when maximised.