Update packaging to 16.7

This adds support for the deprecated python_implementation marker
which was an undocumented setuptools marker prior to 20.2 in
addition to the newer markers.

Move Python 2.6 exception into specific test, capturing that the expected order is different on Python 2.6, not because of the lack of OrderedDict, but because of different behavior in RawConfigParser. Ref #553.

Use OrderedDict to retain deterministic ordering of version info in egg_info command. Remove lexicographic ordering in setopt.edit_config. Ref #553

egg_info is the dictionary with information that is injected
into setup.cfg. edit_config uses RawConfigParser which uses
collections.OrderedDict for all the data. When we use a
simple dict(), when we loop through items in edit_config, we
see random behavior as a result the fields
tag_svn_revision/tag_date/tag_build are added to the setup.cfg
randomly. So if we sort the items by key when we traverse items
we will get deterministic output as RawConfigParser uses
OrderedDict internally by default.

bump certifi to 2016.2.28

Handle not-zip-safe egg (folder) deletion in rotate command

remove _markerlib from manifest

Signed-off-by: Gabi Davar <grizzly.nyo@gmail.com>

Signed-off-by: Gabi Davar <grizzly.nyo@gmail.com>

Update rationale for the zip_safe flag

Importing from a zip file no longer significantly reduces the number
of stat calls during import, and may even slow imports down if
too many archives are added to sys.path.

The outdated rationale was noted by Thomas Güttler on distutils-sig

Swap out hard tabs for spaces

Instead of reasing a new exception, just augment the existing exception, avoiding any concerns about exception type, but still communicating the context necessary to trace the issue. Ref #537.