Checks if update-rc.d (Ubuntu) or chkconfig (RHEL) should be used.
Adds basic bin path search for those binaries
Adds 'enable' and 'disable' options for 'enable' command since it's the
arguments that update-rc.d uses (this might be somewhat confusing to
have a command line with 'enable=enable', but probably mkes sense for
Ubuntu users).
Allows use of mixed case for 'list' and 'state' commands.