Replace primary data Telerik Table

[geofranzi]

several problems could be solved:
#744
#730
#641
sorting sometimes not possible
not all missing values can be substituted correctly (date)

• function to return JSON with already replaced missing values (do it clientside)
• provide all needed functions for server-side paging, filtering, sorting required by datatables (https://datatables.net/manual/server-side)
• decide where / what to search / filter should be possible
• Data structure: Date missing values not replaced #641
• create a view to use a data in the new table