Fix HNAS driver confusing error message (iSCSI driver)

[Erlon R. Cruz]

The error message shown in HDS HNAS ISCSI driver when the parser finds a parser error says, 'file not found' which causes confusion on the user when he/she needs to debug the real cause o the problem.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/147307

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/147307
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=450a35e21f6c102c35dc29e1f684d3588e005ac6
Submitter: Jenkins
Branch: master

commit 450a35e21f6c102c35dc29e1f684d3588e005ac6
Author: Erlon R. Cruz <email address hidden>
Date: Thu Dec 18 16:11:48 2014 -0200

    Fix HNAS driver confusing error message (iSCSI driver)

    The error message shown when the parser finds a parser error
    says, 'file not found' which causes confusion on the user when
    he/she needs to debug the real cause of the problem. This patch fixes
    this by testing first if the file exist and then throwing a proper error
    message.

    Also corrects an error when appending the config_file_name to the message on
    the NFS driver and fixes LOG messages according to oslo.i18n guidelines.

    Closes-Bug: #1403986
    Change-Id: Ib6e613796eede751215db54696b353431caaafd1