Description of problem:
-----------------------
When the creation of VDO volume fails, gdeploy should halt the execution.
The expectation here is the availability of the param 'ignore_vdo_failure' similar to the ones under 'vg' & 'lv'

Version-Release number of selected component (if applicable):
-------------------------------------------------------------
gdeploy-2.0.2-22.el7rhgs

How reproducible:
-----------------
Always

Steps to Reproduce:
-------------------
1. Provide a non-available device for VDO volume creation in gdeploy conf file
2. Execute the conf file

Actual results:
---------------
gdeploy ignore errors when VDO volume creation fails and proceeds to further tasks

Expected results:
----------------
gdeploy should provide an option 'ignore_vdo_errors' there gdeploy could halt the execution on encountering errors

Additional info:
----------------
For example this is the gdeploy conf file used:
[hosts]
host1

[vdo]
action=create
devices=sdz
names=vdovol1
logicalsize=100G
ignore_vdo_errors=no

And here is the console output with the above mentioned gedploy conf file:

# gdeploy -c vdocreate.conf 

PLAY [gluster_servers] ********************************************************************************************************************************************************************************************

TASK [Create VDO with specified size] *****************************************************************************************************************************************************************************
failed: [10.70.36.244] (item={u'disk': u'/dev/sdz', u'logicalsize': u'100G', u'name': u'vdovol1'}) => {"changed": false, "err": "vdo: ERROR -   Device /dev/sdz not found.\n", "item": {"disk": "/dev/sdz", "logicalsize": "100G", "name": "vdovol1"}, "msg": "Creating VDO vdovol1 failed.", "rc": 2}
	to retry, use: --limit @/tmp/tmpaanGEu/vdo-create.retry

PLAY RECAP ********************************************************************************************************************************************************************************************************
10.70.36.244               : ok=0    changed=0    unreachable=0    failed=1   

Ignoring errors...