Fix logging for keystone under mod_wsgi

When Keystone is configured under mod_wsgi, Keystone configuration 
requires debugging to be enabled as the debug flag cannot be passed
via cli arguments.

Because Apache 2.2 (default for a number of distributions) does not 
support passing an explicit format to the ErrorLog, Keystone under 
mod_wsgi ends up with duplicated timestamps in the Keystone log. 
This patchset eliminates the %(asctime) and %(msecs) substitution 
targets from the log format options when Keystone is configured 
under mod_wsgi.

Change-Id: I0bf32db6e53cb653921162cb1957eb988b819815
Force TFTP to listen on IPv4 endpoint

On Fedora with the default configuration TFTP will listen only
on IPv6 endpoint, making imporrible for a node to reach TFTP.
This patch forces TFTP to listen on IPv4 endpoint by modifying
Xinet.d template.

Change-Id: I1ed315fae38816c8e0c2a736261d1c3736f437ff
Better "exec 3>&1" comment

"Copy stdout to fd 3" is confusing. Explain the intention behind `exec 3>&1`.

Change-Id: Id19434121876e65a14c709beac26b9daf4a36a0a
Merge "Better "exec 3>&1" comment"
Merge "Fix logging for keystone under mod_wsgi"
Merge "Force TFTP to listen on IPv4 endpoint"
Merge branch 'master' of https://github.com/openstack-dev/devstack