Implementation of card_ctl function with SC_CARDCTL_GET_SERIALNR

Implementation of card_ctl function with SC_CARDCTL_GET_SERIALNR
Indenting fix and stronger limit on serial number length.
itacns_get_serialnr(): relaxed checking on sc_select_file returned length, added debug log.
itacns_get_serialnr(): check sc_read_binary() returned data length.
itacns_get_serialnr(): check sc_read_binary() returned data length.
itacns_get_serialnr(): check sc_read_binary() returned data length (only).
Merge pull request #321 from resoli/master

Implementation of card_ctl function with SC_CARDCTL_GET_SERIALNR