Update redstack to Fedora 22

[Pete MacKinnon]

A recent change provided a refresh of the Fedora support in redstack and its elements for F21. F22 is actually the current release, the DIB default cloud image, and now has packages for percona-xtrabackup. This change proposes to:

- make dnf (instead of yum) the new default Fedora package manager for redstack and the Trove elements
- update mysql and mariadb elements to make use of the Fedora distro version of percona-xtrabackup
- undo some unfortunate hacks needed in F21 relating to pip and the python-six library
- miscellaneous SSH file permission fixes for Fedora

As before, this change in itself does not necessarily provide complete and tested dev images for ALL the current datastores, but instead focuses on mysql 5.6 and mariadb 5.5.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/229595

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/229595
Committed: https://git.openstack.org/cgit/openstack/trove-integration/commit/?id=b96d76893c7af7ea10c459dc453d31e3c812876e
Submitter: Jenkins
Branch: master

commit b96d76893c7af7ea10c459dc453d31e3c812876e
Author: Peter MacKinnon <email address hidden>
Date: Wed Sep 30 19:53:19 2015 +0000

    Update redstack to Fedora 22

    A recent change provided a refresh of the Fedora support
    in redstack and its elements for F21. F22 is actually the
    current release, the DIB default cloud image, and now has
    packages for percona-xtrabackup. This change proposes to:

    - make dnf (instead of yum) the new default Fedora package
    manager for redstack and the Trove elements
    - update mysql and mariadb elements to make use of the
    Fedora distro version of percona-xtrabackup
    - undo some unfortunate hacks needed in F21 relating to
    pip and the python-six library
    - miscellaneous SSH file permission fixes for Fedora

    As before, this change in itself does not necessarily
    provide complete and tested dev images for ALL the current
    datastores, but instead focuses on mysql 5.6 and mariadb 5.5.

    Now, the DIB_RELEASE will default to 22 and a kick-start can
    be issued as:
    MYSQL_HOST=127.0.0.1 DISTRO=fedora ./redstack kick-start mysql

    Change-Id: I5f195ea7e8ab4d5b8e97801d82d0897469c811d2
    Closes-Bug: 1501485