UTC ISO8601 from timestamp

Taken from glance xattr.py module. This function converts timestamp
formated dates into a UTC Iso 8601 date. It is being required in
multiple places now (mostly on clients printing dates) in order to make
dates human readable.

Change-Id: I6f19325a4c2df241a0ef76bd256280a2930d9265
Allow update.py to copy tools

With first tool: flakes.py

Change-Id: Ie7880927c74ceff174b3b0d2730c499790650921
Import timeutils.is_soon from keystoneclient

This is a function defined as will_expire_soon at least twice in
python-keystoneclient, and it's actually quite handy. There is a comment on
that code about moving to timeutils, and it actually sounds like a good idea
since I'm likely to use it in Ceilometer, so here it is.

Change-Id: Idf208ce9e7ce9048a38d98212b7f730c6b7c8288
Signed-off-by: Julien Danjou <julien@danjou.info>
Merge "Import timeutils.is_soon from keystoneclient"
Merge "UTC ISO8601 from timestamp"