Fix crash in swift-ring-builder's list_parts command.

If you run list_parts against a builder that has never been
rebalanced, you'd get a crash. Now you don't.

To reproduce:

$ swift-ring-builder foo.builder create 8 3 1
$ swift-ring-builder foo.builder add r1z1-1.2.3.4:6000/sda 100
$ swift-ring-builder foo.builder list_parts z1

Change-Id: Ic3edffab0c5c2e9551a2f89ddb881153f0b07db7
swift-ring-builder blows up when not supported command requested.

swift-ring-builder uses outdated unbounded class method to handle
not supported command. It worked for python 2.6 or older but not
for python 2.7 or newer. This patch fixes the problem.

Change-Id: I7dbc681ef6be44f6d79ff93189ccca13c51eab74
Fixes: bug #1154882
Instruction for multi node setup misses /var/run/swift creation

Multiple Server Swift Installation (Ubuntu) instruction does not
indicate that the directory /var/run/swift needs to be created.
That directory actually needs to be created and the ownship needs
to be changed to the user/group which swift service runs under.

This patch will fix the document and gives the steps how to create
the directory and set the ownership right. It also gives instruction
on how the script can be added so that swift services can be resarted
after system reboots.

Change-Id: Id61aa67cc0d6f66d749701e6ea824b1ff3b2c478
Fixes: bug #1156631
Merge "Fix crash in swift-ring-builder's list_parts command."
Merge "Instruction for multi node setup misses /var/run/swift creation"
Merge "swift-ring-builder blows up when not supported command requested."