Minor adjustments of empty page design

On the empty files page the light grey text still uses "assets" instead of "files" ("It looks like you don`t have any assets to display.").Please change the text and replace "assets" with "files".

The empty projects page still shows a drop-down menu ("Add new") where you can only select "Timeline". Please replace the drop-down menu with a button ("create timeline"). This change will also make sure that the layout matches the layout of the files page.