no one uses macports

update the dev docs for OS X to use Homebrew instead of macports, and
reflect the necessary dependencies for 10.9 Mavericks (2013) instead of
10.7 Lion (2011).

Change-Id: Ia1a06a15b9f03777fe9d3e77a37eb395f15a4706
replaced unicode() with six.text_type()

According to https://wiki.openstack.org/wiki/Python3 unicode()
should be replaced with six.text_type().

Change-Id: I7e6119d66b7ad51e4a8ee7b3d8ce4188e321a08b
indicate that sensitive messages can be disabled

Change-Id: I5b52ebe996457f2766939e1a66dbeed3dc5869c4
Closes-Bug: 1322187
Merge "replaced unicode() with six.text_type()"
Merge "no one uses macports"
Merge "indicate that sensitive messages can be disabled"