Refactor delpub-commands, Allow multiple channels

Refactor delpub-commands, Allow multiple channels

Refactor the implementation of redis commands: DELPUB, DELIEPUB
and DELNEPUB to make more clear which parts of the old implementation
are specific to each command.

Allow multiple channels as parameter in the redis commands
DELIEPUB and DELNEPUB.

New syntaxes:
DELIEPUB key oldvalue channel message [ channel message .. ]
DELNEPUB key oldvalue channel message [ channel message .. ]

Signed-off-by: Arvo Heinonen <arvo.heinonen@nokia.com>
Change-Id: I3dfb86ed4c8951bb395aff053b9c2bb898cfd0a4

Remove old delpub command implementation

After refactoring the old delpub command implementation in
'delPubStringGenericCommand' is no longer used. Remove it.

Signed-off-by: Arvo Heinonen <arvo.heinonen@nokia.com>
Change-Id: I77817744aea6c78226e8cab8aebbd401efe63c40