behavior when percentDialog closes

- checkbox gets checked
- navigation drawer gets closed
added greyscale to the example app

added greyscale to the example app and I removed the according javadoc
from the library
possibility to change the % sign

possibility to change the % sign, no sure if someone ever will use
this, but why not :)
custom colourdialog, javadoc

- added a custom rub color choosing dialog
- added some javadoc
- added the @since 1.4.0 javadoc to the new stuff