Shadow property added

Shadow is ON by default. It can be simply changed to OFF by setting NO
to badgeShadow property.
Merge branch 'shadow-property' of https://github.com/SerJG/CustomBadge into SerJG-shadow-property
Merge branch 'SerJG-shadow-property'
CustomBadge Version 3: Introducing separation between style and rendering + iOS7+8 Font + Shadow on/off