fixing the iSER transport protocol when using LVMISERDriver

ISER capabilities were broken in icehouse when trying to remove
duplication between ISCSIDriver and ISERDriver.

This fix does minimal changes in the code in order to fix
the capability.

The fix is basically re-adding the ISERTgtAdm and re-adding
the support in LVMISERDriver: change target_lun based on
iseradm.

Conflicts:
        cinder/volume/driver.py

Changes from the original fix in Juno:

Bug https://bugs.launchpad.net/cinder/+bug/1325799
caused the volumes to be created with iSCSI's prefix
parameter in any case. In order to solve the prefix mismatch,
iSER's prefix is updated to match iSCSI’s prefix.
The related changes:
  1. cinder/brick/iscsi/iscsi.py line 614
  2. Cinder/volume/driver.py line 118
  3. etc/cinder/cinder.conf.sample line 921

Closes-Bug: #1336648
Change-Id: Ic3c9da9577d09d9199218ea82bda56599527223c
(cherry picked from commit f66f9e5805070e5ad2ba4688c6c4571ef1ec395a)
Merge "fixing the iSER transport protocol when using LVMISERDriver" into stable/icehouse