Workaround bug in yum python API

This works around a bug in the yum python API where removal of packages
that are required by other packages results in the removal of those
packages as well, and does not raise an exception when errors are
encountered during the transaction test, causing all packages to be
removed.

This commit manually performs the transaction test, and raises an
exception if any errors are found. It also adds a try/except to the
pkg.removed and pkg.purged states which catches the exception and
gracefully returns False without a traceback.

See https://github.com/saltstack/salt/issues/8201 for more information.
Merge pull request #8203 from terminalmage/issue8201

Workaround bug in yum python API
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fix function： leaks，serverinfo

#salt 'web-87' tomcat.leaks
web-87:
    F
    a
    i
    l
    e
    d
     
    t
    o
     
    c
    r
    e
    a
    t
    e
     
    H
    T
    T
    P
     
    r
    e
    q
    u
    e
    s
    t

#salt 'web-87' tomcat.serverinfo
web-87:
    ----------
    error:
        F
Document setting a whitelist firewall ruleset on the Master
Merge pull request #8206 from pyinx/patch-2

fix function： leaks，serverinfo
Revert the section title change
Merge pull request #8208 from holmboe/doc-whitelist-firewall

Document setting a whitelist firewall ruleset on the Master
Merge pull request #8209 from holmboe/doc-whitelist-firewall

Revert the section title change
Switch 0.15.1 release notes back to unix line endings

Line endings got switched in 2f869f8. Fixes #8204
Make sure we're getting a dict
Merge pull request #8214 from UtahDave/develop

Make sure we're getting a dict
Updated downloads URL for Windows binaries
More aggressive exception handling and retry logic. Refs #7755.
Import logging.
Skip malformed files during reaping. We can just as easily catch them the next time.
Merge pull request #8219 from cachedout/#7755

#7755 More aggressive re-try logic
Merge pull request #8220 from cachedout/warn-on-reap

Skip malformed files during reaping. We can just as easily catch them th...
Modify system shutdown command.

New flag to shutdown at a given time. Refs #7833.
Silence Pylint warning.