some visual changes for FileExplorer, fixes #1237
    - hide some UI elements until knockout is ready (editor, new folder view, table rows, error sign)
    - set "Site Root" icon to on by default and hide it if there are no Site Root. Basically optimize for Azure, rather than the other way around
    - fix the columns with in the table
    - set default value '/' to folder name and '0' to items count