added 'head' class to the templates for PostItView and PostItGroupView in order to debug circular event handling in the header model updates
changes templates for postIt and PostItGroups to avoid duplicate event handling
BUGFIX: made the CSS selectors used to get and set the header text in the PostItGroup DOM more specific
BUGFIX: made the CSS selectors used to get and set the header text in the PostIt DOM more specific
removed console logs and global vars used for debugging