Remove default OCDB location and exit with fatal error if OCDB URI is

Remove default OCDB location and exit with fatal error if OCDB URI is
not passed (or OCDB default-storage is already set).

The OCDB URI is now the first argument of alieve_init.C and
visscan_init.C.

To simplify standard usage, several wrapper macros have been added:
  visscan_raw.C         - SetDefaultStorage("raw://");
  visscan_mcideal.C     - SetDefaultStorage("MC, "Ideal");
  visscan_mcresidual.C  - SetDefaultStorage("MC, "Residual");
  visscan_mcfull.C      - SetDefaultStorage("MC, "Full");
  visscan_local.C       - SetDefaultStorage("local://$ALICE_ROOT/OCDB");