[Ch24 - update] Added State List Drawable

Added:
+ implemented State List Drawable

Notes:
+ <item><color…></item> does not seem to work. Instead, colour has to
be defined inline with the item tag.
+ K, nvm, whole documentation on it says that colour is an attribute of
item:
http://developer.android.com/guide/topics/resources/color-list-resource.
html