Implement notes & note-sync (#32)

* Create Notes & Whiteboard components and classes

* sync changes

* add fabricjs whiteboard

* fix imports

* add zoom and panning to whiteboard

* note component

* sync note changes to backend

* improve code

* remove unused var

* improve code

* fix build errors

* fix build errors

* fix prettier

* fix notes.vue

* add delete note function

* Add download option to a note

* remove obsolete function

* update loadNotes