The CLI 'gluster system:: execute mountbroker user <USERNAME> <VOLUMES>'
to set volumes associated with a user replaces existing user and associated
volumes upon setting with existing user. This patch fixes it by appending
the volumes if the user already exists.

It also introduces following CLI to remove volume for a corresponding user.

'gluster system:: execute mountbroker volumedel <USERNAME> <VOLUME>'
<USERNAME>: username
<VOLUME>: comman separated list of volumes to delete

If it is the last volume to be deleted associated with the user,
it will delete the user as well as it doesn't make sense to keep
only user without volumes associated.

Change-Id: I4c7240ce912e1b836794bf0682a5fc6e5b2adc70
BUG: 1235428
Reviewed-On: http://review.gluster.org/11385
Signed-off-by: Kotresh HR <khiremat@redhat.com>
Reviewed-on: http://review.gluster.org/11386
Tested-by: NetBSD Build System <jenkins@build.gluster.org>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Milind Changire <mchangir@redhat.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

Non root geo-replication setup is now simplified. This
patch provides cli for mountbroker user and options management

To set Options,
    gluster system:: execute mountbroker opt <KEY> <VALUE>
    # for example,
    gluster system:: execute mountbroker opt mountbroker-root /var/mountbroker-root
    gluster system:: execute mountbroker opt geo-replication-log-group geogroup
    gluster system:: execute mountbroker opt rpc-auth-allow-insecure on

To remove option,
    gluster system:: execute mountbroker optdel <KEY>
    # for example,
    gluster system:: execute mountbroker optdel geo-replication-log-group

To add/edit user,
    gluster system:: execute mountbroker user <USERNAME> <VOLUMES>
    # for example
    gluster system:: execute mountbroker user geoaccount slavevol1,slavevol2

To remove user,
    gluster system:: execute mountbroker userdel <USERNAME>
    # for example
    gluster system:: execute mountbroker userdel geoaccount

For info,
    gluster system:: execute mountbroker info
    gluster system:: execute mountbroker -j info

For JSON output add -j after mountbroker, for example,
    gluster system:: execute mountbroker -j user geoaccount slavevol1,slavevol2

PS: Each peer prints its own JSON output, aggregator required from consumer side

BUG: 1136312
Change-Id: Ie52210c0bcc91ac2ffd3ba58988222ffca62b47f
Signed-off-by: Aravinda VK <avishwan@redhat.com>
Reviewed-on: http://review.gluster.org/9398
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: darshan n <dnarayan@redhat.com>
Reviewed-by: Kotresh HR <khiremat@redhat.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>