Use of Version within the placement service has made it clear
that the Version object knowing the min and max versions is
useful when making Version.matches comparisons.
Therefore the matches method has been updated to refer to
min_version and max_version attributes if they are not set
in the matches() request. The extract_version function now
sets those attributes based on the version_list that is
passed to it.
If min and max are not set on the Version object, they default
to negative versions, which are not possible in microversions
and mean matches() (without override args) will be false. The
use of explicit values (instead of None) is so python3 is happy
(and it is better anyway).
Change-Id: I71d091d037abcd068601b32722a09094ae74e658
e346558d5f