Implemented EditableTemplatedWidget

EdtableTemplatedWidget is supposed to be the common base constructor for
all wikibase.*view widgets. ->72666

Change-Id: Ib21c2d50d1acd0c32024ad226956cd0840fe3e13
Implemented EventSingletonManager

Implemented $.util.EventSingletonManager and applied it to $.sticknode plugin.
The utility constructor will be used for solving 73300 as well.

Change-Id: I46fed73ae4ab25284d392ce19b912ee8272b5495
Merge "Implemented EditableTemplatedWidget"
Merge "Implemented EventSingletonManager"