Sync latest processutils from oslo-incubator

Sync latest processutils from oslo-incubator

This sync is primarily being done to pull in commit
63c99a0f so that passwords are masked in exception and
error messages.

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oslo-incubator head:

commit 80a08a413fb0f23a056eca2d273b167f0a09bab6
Merge: 83c4098 d73f3b1
Author: Jenkins <jenkins@review.openstack.org>
Date:   Mon Aug 25 14:32:36 2014 +0000

    Merge "Remove unused/mutable default args"

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The sync pulls in the following changes (newest to oldest):

63c99a0f - Mask passwords in exceptions and error messages
e184dd36 - Fix exception message in openstack.common.processutils.execute
d6b55fb2 - Remove `processutils` dependency on `log`

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Change-Id: Ia92aab76fa83d01c5fbf6f9d31df2463fc26ba5c
Partial-bug: 1343604