Fixed the python tests in the presence of muliple eggs.

Review: https://reviews.apache.org/r/16136
Added stringifier.hpp to stout/Makefile.am.

Review request #15285 breaks 'make distcheck' due to missing entry in
3rdparty/libprocess/3rdparty/stout/Makefile.am for the new stringifier
header. This patch adds the missing entry.

Review: https://reviews.apache.org/r/16161
Printed timezone, full ISO 8601, with timestamps.

The current date format, "2013-12-05 10:08:30", does not include the
timezone and can be confusing when the timezone is different than
expected. Add the timezone and the letter "T" between the date and time
to match the ISO 8601 standard.

"2013-12-05 10:08:30" -> "2013-12-05T10:08:30-0800"

Review: http://reviews.apache.org/r/16096