beta version

• add 'async' attribute on system load via HTML:
  example:
  It will load the system asynchronaly,
• add parameter for collection event change ('add' / 'remove'),
• add a new monoco core addon to specify new types ('css', 'html' and 'javascript'),
• behaviors are now real components: they inherit from MonocoComponent. So behaviors can be updated dynamically with classic component apis,
• $db.remove now returns the list of removed documents,
• 'destroy' and 'init' states of components are now methods (they are no ore events)
• we can now listen to a collection update (ex: .children(0, son) or children.push(son)),
• add $metamodel.isCollection, $metamodel.isMethod,
• update jsdoc and
• add more unit tests