Add js path to event model

[geofranzi]

Add custom based js or css to each event

• allow to upload js / css file to ensure new events can be created without touching the code
• change upload path
• add js / css to model / view
• prepare event.js
• implement Allow external manipulation of metadata edit view BEXIS2/Core#244

(CSS path is skipped / postpond)

[geofranzi]

• access of element by "master" parent to avoid the event is removed during the replacement of the element jQuery('[idbyname=title_general]').parent().parent().parent().parent().parent().parent().change(...)
• create identifier by name (name, parent name, current position, parent position)
• add parent of parent ?