cluster/stripe: Mount issues with Stripe xlator

Problem:
* 'CONNECTING' is taken as CHILD_UP.
* Sending notifications (default_notify()) for all the events individually
   while mounting.

Solution:
* Consider Child up only after the event CHILD_UP is received.
* Send a single notification for all the children's events only
   while mounting.

Change-Id: I1b7de127e12f5bfb8f80702dbdce02019e138bc8
BUG: 885072
Signed-off-by: Varun Shastry <vshastry@redhat.com>
Reviewed-on: http://review.gluster.org/4356
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>