Domain.Medium, TempVisitMedia, Button.isEnabled

Domain.Medium - Visits have Media, Medium have MTags
TempVisitMedia - object to handle uncommited Media(Video & Images)
wMediaDetail simplifyed - preview removed, path is internal

* MTags needs to be implemented on wMediaDetail
* Open Media/View Media Details needs to be implemented
* Grab Image needs to be implmented
* Unsaved/Removed Media cleanup needs to be implemented