bugfix: column reverse not working properly when rating is less than 1

• fix for #25

a11y ready package

• Accessibility properties added for non-readonly element

Minor change to IconBar -> `TouchableOpacity` element

ActiveOpacity set to 1

Adding support for custom images

• onStarTap changed to onIconTap
• support added for custom image
• new props added - type, selectedIconImage and emptyIconImage
• updated readme

Direction aware rating icons v5

Added support for customising direction of icons.
Pass "direction" prop to any value from [ "row", "row-reverse", "column", "column-reverse"].