Fix typos in oslo

Change-Id: Ic2854d6ba6c40df6c4d5e01c1f4780dd6b2cded1
Add TempHomeDir fixture which is already part of cookiecutter template

TempHomeDir fixture creates a temporary directory and sets it as $HOME in the
environment. Also tearDown will remove it and reverts back $HOME value to
the previous one.

1. In one of the review comments for https://review.openstack.org/#/c/55111,
   russellb suggested to add TempHomeDir fixture to test module.

2. Cookiecutter template for OpenStack based projects already has this.

Change-Id: I7bd86a9d1e1951e04a632cecb181fc1e2c30f392
Add mask password impl from other projects

A couple of different projects have an implementation for 'masking'
passwords in logs and wsgi output.

This seems like something that should go into Oslo-incubator as a common
implementation. This implementation is based off the following two
implementations in Keystone and Nova:

  https://review.openstack.org/#/c/26487/12
  https://review.openstack.org/#/c/49664/

Partial-Bug: #1247217

Change-Id: I2b1bbb4d3ddaa163573b685b3e3a5e8a3977e390
Merge "Add TempHomeDir fixture which is already part of cookiecutter template"
Merge "Add mask password impl from other projects"
Merge "Fix typos in oslo"