Refactor setpub-commands, Allow multiple channels

Refactor setpub-commands, Allow multiple channels

Refactor the implementation of redis commands: MSETPUB, SETIEPUB,
SETNEPUB, SETXXPUB and SETNXPUB to make more clear which parts
of the old implementation are specific to each command.

Allow multiple channels as parameter in the redis commands
SETXXPUB, SETNXPUB, SETIEPUB and SETNEPUB.

New syntaxes:
SETXXPUB key value channel message [ channel message .. ]
SETNXPUB key value channel message [ channel message .. ]
SETIEPUB key value oldvalue channel message [ channel message .. ]
SETNEPUB key value oldvalue channel message [ channel message .. ]

Signed-off-by: Arvo Heinonen <arvo.heinonen@nokia.com>
Change-Id: If1c99f54148140f76a213d3a88269bd4fc83e49c