refactor C4::Log::logaction

refactor C4::Log::logaction

This fix should resolve in whole or in part several bugs
characterized by the error message 'Can't use string ("0")
as a HASH ref while "strict refs" in use', including
bugs 1101, 1899, and 1910.

There are some possibilities for future work:

[1] Dealing with an operator override, e.g., where
    a circ operator needs to get a supervisor
    to enter a login and password and escalate
    the original operator's privileges for a
    transaction, e.g., to forgive a fine.  This
    is an enhancement, of course.
[2] Creating a dummy operator to represent
    batch job runs; or alternatively, give
    each batch job an option to log its work
    under a specified user ID.

Signed-off-by: Joshua Ferraro <jmf@liblime.com>