Fix patron blocking in LookupUser

Not all standing penalties in Evergreen should cause a value to be
returned in the LookupUser BlockOrTrap element.

Uncomment existing code (originally from issa -- thanks, @Dyrcona!)
to iterate over penalties and only block on those whose block list
contains a certain set of block types.

We are now blocking only on standing penalties that contain HOLD or
CIRC in their block list.

Fixes #14.

Signed-off-by: Jeff Godin <jgodin@tadl.org>