Update README with rationale and internal mirror

Added why folks need to add their projects here and what it
will help with

Change-Id: Ia57e1197de8ad32fb819d1bd211b37b82db63518
Adds python-seamicroclient dependency for Ironic

* python-seamicroclient>=0.1.0,<2.0 required for Ironic project
* required due to (https://review.openstack.org/#/c/70719/)

Change-Id: I134ff9e841d31d266fa7b9f41963260449c25394
Remove tox locale overrides

* tox.ini: The LANG, LANGUAGE and LC_ALL environment overrides were
introduced originally during the testr migration in an attempt to be
conservative about the possibility that locale settings in the
calling environment could cause consistency problems for test runs.
In actuality, this should be unnecessary and any place where it does
cause issues ought to be considered an actual bug. Also, having
these in the configuration actively causes older pip to have
problems with non-ASCII content in some package metadata files under
Python 3, so drop it now.

Change-Id: I47affb3524a40c736c7bc1d9cd455b98c9d49273
Closes-Bug: #1277495
Merge "Update README with rationale and internal mirror"
Merge "Remove tox locale overrides"