Merge lp://qastaging/~sinzui/launchpad/commercial-admin-private-teams into lp://qastaging/launchpad

This is my branch to permit commercial admins to see private teams.

    lp:~sinzui/launchpad/registry-rename-0
    Diff size: 97
    Launchpad bug:
          https://bugs.launchpad.net/bugs/613791
    Test command: ./bin/test -vv -t private-team-visibility
    Pre-implementation: bigjools
    Target release: 10.09

Permit commercial admins to see private teams
---------------------------------------------

Commercial admins have been asked to help private teams resolve setup and
launchpad usage issues, but they cannot see the team to help. Canonical
groups, canonical partners, and commercial users expect the people who help
setup private teams be able to help resolve issues.

Rules
-----

    * Add commercial admins to the launchpad.View rules for private teams.

QA
--

    * As a commercial admin verify you can see a private team that you are not
      a member of.

Lint
----

Linting changed files:
  lib/canonical/launchpad/security.py
  lib/lp/registry/doc/private-team-visibility.txt

Test
----

    * lib/lp/registry/doc/private-team-visibility.txt
      * Updated the doctest to show who is permitted to see private teams.

Implementation
--------------

    * lib/canonical/launchpad/security.py
      * Added commercial admins the launchpad.View on private teams and
        TeamMemberships (which are implcitly private if the team is private).