fuelclient raise an access error when trying to render graph

[Sebastian Kalinowski]

When trying to render some file with graph:
 fuel graph --render out.gv
and when the output file do not exists on disk, an error is raised:

Path /mirantis/fuel/python-fuelclient/out.gv.png is not writable

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/165439

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/165439
Committed: https://git.openstack.org/cgit/stackforge/python-fuelclient/commit/?id=57c7f9ed801174b55bf2385e249d5425a3327252
Submitter: Jenkins
Branch: master

commit 57c7f9ed801174b55bf2385e249d5425a3327252
Author: Sebastian Kalinowski <email address hidden>
Date: Wed Mar 18 15:43:11 2015 +0100

    Fix check for write access during graph render

    Do not check for access for output file since it will
    fail when it doesn't exists - check only if the target dir is writable.

    Change-Id: I7ef696890173f5239a7b6c073e86ee3648537b55
    Closes-Bug: #1433634