completed molecular pcr worksheet functions

replaced M::Request::get_request_from_lab_number() method using multiple db lookups with get_request_id_from_lab_number() using single db lookup

corrected rounding error in user_workload.tt; added params to plasmacell data collection template

check_portal_referral failure redirects to location-specific home page to allow targetting correct fastcgi process; moved hmrn.patient_treatment.response to foreign key -> response_options table; logo filename dispatched from settings file