Enable live block migration when using iSCSI volumes

Fix for bug 1160323.

DocImpact
Depends on a version of XAPI supporting relax-xsm-sr-check.
Currently no release versions support this, so the change at
https://github.com/xen-org/xen-api/pull/1116 would need to be applied
to the source to enable this.  XenServer 6.2 is expected to
support this mode, and possibly some future hotfixes for XenServer 6.1.

It also depends on a configuration change which must be documented and added to devstack:
* Set "relax-xsm-sr-check = true" in /etc/xapi.conf

This commit makes the following changes:
* Attach the SR on the destination host prior to migrate
* Returns the SR-ref from the pre_migrate call (API change)
* Populates the XS VDI map with the sr-ref on the destination host
* Removes the connection to the SR from the source host post-migrate
* Added plugin to determine if iSCSI block migration is enabled

Associated tempest test at https://review.openstack.org/#/c/26478/

Change-Id: I917d9cf094190d636f4b9e14f6c8e728ff85af0e
Fixes: bug 1160323
Fixes KeyError bug with network api associate

Fixes bug in network api associate function where it would always
raise a KeyError when associating or disassociating a project.

Fixes bug 1171284

Change-Id: Iae0e57e0a961b8a3377b38dad72094188755a3e8
Fix zookeeper import and tests

Import zookeeper.membership rather than zookeeper.membersip.
Also fixed some issues with setting up the tests for the zookeeper
servicegroup driver.  Config options were not being set before
initializing the driver leading to failures.

There is no added test for this because the bug is indistinguishable
from not having the zookeeper python modules installed, which leads to
skipping these servicegroup tests.

Bug 1177776

Change-Id: Idd6dca2e03169399b930cc1fc1a85636497cb0b5
Imported Translations from Transifex

Change-Id: I6682277f9796779773f60336e240487e6409f0f7
Record smoketest dependency on gFlags

The smoketests currently have a dependency on gFlags. Long term, this should
be converted to use openstack.common.cfg; but in the near term, we should
record this existing dependency.

Fixes bug 1174953

Change-Id: I465abc6a4a2e8f7ebd1fe70ad239c760960a82ed
Merge "Record smoketest dependency on gFlags"
Merge "Fixes KeyError bug with network api associate"
Merge "Fix zookeeper import and tests"
Merge "Enable live block migration when using iSCSI volumes"