libglusterfs: Fixed valid_ipv4_address and valid_host_name

In valid_ipv4_address(), strtok_r was ignoring consecutive dots,
and was marking any address with consecutive dots as valid. Now
such addresses will be marked as invalid.

In valid_host_name(), any name ending with any special characters
was marked as valid. Now such hostnames will be marked as invalid.

Change-Id: If9b625d9040a14bde8c176fe36e337cb483e284a
BUG: 822830
Signed-off-by: Avra Sengupta <asengupt@redhat.com>
Reviewed-on: http://review.gluster.org/4579
Reviewed-by: Jeff Darcy <jdarcy@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>