Make it possible to choose the bouncing type for dock icon (once, infini...

Hey there, some review necessary, as it is my first Objective-C work (basically copied other code I found in the project).

This commit makes it possible to choose whether the dock icon bounces once or to infinity in the trigger. Some issues I am not sure about:

 - It changes the params, so maybe there is something to do about profile configurations?
 - I am not sure how the default value is choosen with that.
 - Can't `NSRequestUserAttentionType` be used as values directly in the dictionary?
 - Is there a test suite in the project?

Feedback much appreciated! Another patch coming after those things are figured out!