add a radio button to activate the option for clearing bed assignments

[jcjcx1]

the option to clear bed assignments (either to nuke the entire thing, or just remove 1 person) is disallowed when a person is selected from the signup list. however, it is not obvious how to deselect a person so as the re-activate the 'remove' option (even adding the selected person to a bed does not deselect them).

add a button: perhaps label it "activate bed clearing" or "deselect a person"