RHEL/EPEL yum-based install for Dashboard and restart needs fixes

[Anne Gentle]

Reported at http://docs.openstack.org/essex/openstack-compute/install/yum/content/ch_install-dashboard.html#comment-590117451

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use "yum install -y memcached mod_wsgi openstack-dashboard" instead of " yum install -y memcached libapache2-mod-wsgi openstack-dashboard" to install dashboard on CentOS6

use "service httpd restart" instead of "/etc/init.d/apache2 restart" to restart apache2
use "./usr/share/openstack-dashboard/manage.py runserver 0.0.0.0:8080" to start dashboard,otherwise you will see the apache2 welcome page.Rember do not use root user to visit dashboard,otherwise you will get 500 Internal error.
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Looks like a straightforward doc fix.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/9934

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/9934
Committed: http://github.com/openstack/openstack-manuals/commit/f7cb2ff86d8d539042e897e4badbead3c7d6ac9e
Submitter: Jenkins
Branch: master

commit f7cb2ff86d8d539042e897e4badbead3c7d6ac9e
Author: annegentle <email address hidden>
Date: Tue Jul 17 14:03:42 2012 -0700

    Adds text to explain intro arch diagram, updates dashboard install.

    Fixes two doc bugs: bug 1025847, bug 1025840

    Change-Id: I7bd348349ef49d581cbaf284497d13816535a11d

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/essex
Review: https://review.openstack.org/9984

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/9984
Committed: http://github.com/openstack/openstack-manuals/commit/dcaeadc200244d147fef7ba52764a0dd2b81eb29
Submitter: Jenkins
Branch: stable/essex

commit dcaeadc200244d147fef7ba52764a0dd2b81eb29
Author: annegentle <email address hidden>
Date: Tue Jul 17 14:03:42 2012 -0700

    Adds text to explain intro arch diagram, updates dashboard install.

    Fixes two doc bugs: bug 1025847, bug 1025840

    Commits a cherry-pick https://review.openstack.org/#/c/9934/

    Change-Id: I7bd348349ef49d581cbaf284497d13816535a11d