Build images with a 4k block size filesystem

This will support both 512b and 4k disks.

Change-Id: I1e64647b3de86bc87a2a04cedf54ac83bbd4963d
Closes-Bug: #1746727

image-yaml/overcloud-images-centos7.yaml

@@ -9,6 +9,8 @@ disk_images:
       FS_TYPE: xfs
     packages:
       - yum-plugin-priorities
+    options:
+      - "--mkfs-options '-s size=4096'"
   -
     imagename: ironic-python-agent
     type: qcow2

image-yaml/overcloud-images-rhel7.yaml

@@ -5,6 +5,8 @@ disk_images:
     distro: rhel7
     environment:
       FS_TYPE: xfs
+    options:
+      - "--mkfs-options '-s size=4096'"
   -
     imagename: ironic-python-agent
     type: qcow2

tripleo_common/image/image_builder.py

@@ -17,6 +17,7 @@
 import abc
 import logging
 import os
+import shlex
 import six
 import subprocess
 import sys
@@ -94,7 +95,7 @@ class DibImageBuilder(ImageBuilder):
 
         if options:
             for option in options:
-                cmd.extend(option.split(' '))
+                cmd.extend(shlex.split(option))
 
         skip_base = extra_options.get('skip_base', False)
         if skip_base: