Use file.check_perms to enforce ownership/permissions

The fix that I made in #8417 was incomplete in that it did not work on
symlinks. This uses an existing execution module function,
file.check_perms, to enforce the ownership and permissions.
Merge pull request #8366 from JustinCarmony/composer-states

Work in Progress for Composer Support for Salt
Merge pull request #8467 from kula/ext-pillar-doc-update

Update ext_pillar documentation for new ext_pillar signature
Merge pull request #8468 from krak3n/feature/pip-documentation-improvment

Slightly improved pip state usage documentation.
Merge pull request #8471 from whiteinge/django_orm-enhancements

Django orm enhancements
Merge pull request #8469 from heewa/open_mode_key_fix

Always save minion key in open mode.
Merge pull request #8475 from terminalmage/issue8418

Better reporting for rendering errors + jinja render error fix
Merge pull request #8477 from terminalmage/issue8399

Fixes for #8417
Make minion ID caching configurable
Add last two things to 0.17.2 release notes
Merge pull request #8488 from basepi/minion_id_config

Make minion ID caching configurable
Merge pull request #8489 from basepi/0.17.2

Add release notes for 0.17.2
pylint fixes for composer state
fix pylint and first person docs
lint error in new cloudclient, still needs more attention
Clean out unreachable code
whitespace fix in composer
First pass at removing pylint errors
Merge pull request #8490 from cro/gnomedesktop_pylint

First pass at removing pylint errors
More pylint fixes.