tweak columns for picklist and purchase order grids

tweak columns for picklist and purchase order grids

to better match the spec (unmandated columns hidden by default)

virtual columns such as picklist's entry_count have to be specified with eg-grid

hiding fleshed user columns was causing some uncaught errors and the grid to
misrender when manually unhidden. Adding a label helped, but would render the
cell as [object Object].  Using a cell template to handle that object was
providing different errors (.id() was accessible, but not .usrname()).  So,
unfleshing those for now.

Signed-off-by: Jason Etheridge <jason@EquinoxInitiative.org>