Implement capability to extend existing volume.

This patch adds the core components to implement extending
the size of an existing available volume.

Volume status must be available, and the format is:
    extend <vol-id> <new-size>

where new-size must be > current size.

Adding support to drivers will be handled in follow up
patches for each of the existing drivers.

Implements blueprint: volume-resize

Change-Id: I40026083e564ea2074757e11e13cd07cdae3e6cc
Use Python 3.x compatible octal numbers

Unfortunately, Python 3.x deprecated support for 0755
octal numbers. Use 0o755 instead.

Change-Id: I70403d382d6e6569445b6a99954ea24d436f29ad
cinder.schedule: Replace 'locals()' with explicit values

Help bring source code into compliance with the Cinder Style Commandments:
https://github.com/openstack/cinder/blob/master/HACKING.rst

This change covers all affected source in the cinder scheduler module, i.e.
cinder/scheduler/*.py and subdirectories.

Partially fixes: bug #1190748

Change-Id: I75ad858ee62317bef6c59b9c0896f8a94a989d52
Use common.processutils.execute

This patch replaces the cinder.utils.execute method
with a wrapper around openstack.common.processutils.execute.

With the wrapper I'm also converting the processutils exceptions
to maintain compatability with the existing exceptions that are
caught/raised in the code.

Change-Id: Ibc36a1e83191e7c888ea62c55d28b7023535d9fa
cinder/.: replace 'locals()' with explicit values

Help bring source code into compliance with the Cinder Style Commandments:
https://github.com/openstack/cinder/blob/master/HACKING.rst

This change covers all affected source directly in the top-level directory
of the cinder module, i.e. cinder/*.py

Partially fixes: bug #1190748

Change-Id: Ice5efc5eda7189969af6a9b722344fad7aa49ff0
Merge "cinder/.: replace 'locals()' with explicit values"
Merge "Use Python 3.x compatible octal numbers"
Merge "Use common.processutils.execute"
Merge "cinder.schedule: Replace 'locals()' with explicit values"
Fix and enable gating on H403

Fix occurrences of
H403 - multi line docstring end on new line

Change-Id: I79a818095e9f64a18ded1686fb152b9d58f3c8b1
Update attach status when instance id invalid.

In cinder.manager do_attach we have a check to make sure the
supplied instance id is a valid UUID which is great, but if it's
not we just raise and dump out, leaving the volume in an attaching
state.

We should update the status to error_attaching in this case and then
raise/return.

Fixes bug: 1192370

Change-Id: Ia759ea7a387544913953ca84e9ed927480c4edfd
Merge "Update attach status when instance id invalid."
Merge "Implement capability to extend existing volume."