Pass authtoken to OpenILS::SIP::Patron objects

Pass authtoken to OpenILS::SIP::Patron objects

To support retrieval of billing details, OpenILS::SIP::Patron
objects need an auth token.

Teach OpenILS::SIP->find_patron to pass patron objects an auth
token, and also move existing "find patron by what key: barcode or
database id?" logic into find_patron (and out of
OpenILS::SIP::Patron->new).

Signed-off-by: Jeff Godin <jgodin@tadl.org>
Signed-off-by: Jason Stephenson <jstephenson@mvlc.org>
Signed-off-by: Dan Scott <dscott@laurentian.ca>