add deprecation note to middleware

we're migrating middleware to alternate libraries. this patch
marks oslo-incubator version as deprecated.

Change-Id: I2f754d8a3aa49a0ea6ddb4e5e161bebb82181017
Implements: blueprint graduate-oslo-middleware
Mask passwords in exceptions and error messages

When a ProcessExecutionError is thrown by processutils.execute(), the
exception may contain information such as password. Upstream
applications that just log the message (as several appear to do) could
inadvertently expose these passwords to a user with read access to the
log files. It is therefore considered prudent to invoke
strutils.mask_password() on the command, stdout and stderr in the
exception. A test case has been added to ensure that all three are
properly masked.

OSSA is aware of this change request.

Submitted to oslo.concurrency in
Ie122db5f19802f519b96ed024ab3f2b5eede3eee

Change-Id: I173dfb865e84eb7dee54a22c76db1e4f125a0a8a
Closes-Bug: #1343604
Remove unused/mutable default args

Having mutable default args is a bad idea
(http://docs.python-guide.org/en/latest/writing/gotchas/#mutable-default-arguments).

The places where a new object would not be instantiated were left alone,
since it wouldn't make any difference (the same object would be
referenced anyway).

Change-Id: If71154d9bdb42f3ee284c4478c3ee7b177ec8009
Merge "add deprecation note to middleware"
Merge "Mask passwords in exceptions and error messages"
Merge "Remove unused/mutable default args"