A valid PicApport Add-on has to implement this interface.
Every time a groovy Add-on is loaded the init() method is called from PicApport
to obtain information(metadata) about the Add-on. Because Maps have very good support in
groovy all information is returned in a map.
It depends on the type of the groovy Add-on which information has to be provided.
see PicApport Add-on Programming reference
for more information about the different Add-on types and their metadata.