Add GlusterFS volume driver

This driver enables use of GlusterFS in a similar fashion
as the NFS driver.  It supports basic volume operations,
and like NFS, does not support snapshot/clone.

To enable, set volume_driver to
 cinder.volume.drivers.glusterfs.GlusterfsDriver

Note that this requires a Nova libvirt GlusterFS driver
as well.

Adds config options: glusterfs_shares_config,
glusterfs_mount_point_base, glusterfs_disk_util, and
glusterfs_sparsed_volumes.

DocImpact

Change-Id: I3dd4018f0cb4db48348728ca66bae7918309bb32
Add LIO iSCSI backend support using python-rtslib

This patch enables LIO as an iSCSI backend for Cinder, using
python-rtslib.

To enable, set "iscsi_helper = lioadm" in cinder.conf.

This requires python-rtslib 2.1.fb27, which is available from pip.

Implements blueprint lio-iscsi-support
DocImpact

Change-Id: Ifb23de65f26a40997afd6148a1d0be39bcc8d196
Merge "Add LIO iSCSI backend support using python-rtslib"
Merge "Add GlusterFS volume driver"