Bug resolved in editing pandora videos metadata

* Bug : 
Previously while editing metadata for pandora videos giving an error as "creating GAttribute for video resource "subject_type" was missing as "Pandora_video" (ST).

* Resolved: 
Now included "Pandora_video" in factory_types.py for all those AT's as their "subject_type" which are required to edit the metadata for pandora videos.
Also removed a bug in ''videodashboard.py" as "assesses_list" was missing in "video_edit()" since it was givin the error 

Now we need to work on saving the metadata for pandora videos,also need to provide the list of values to be entered while editing the metadata, so that user should not make a mistake while entering the metadata.