Revert "Revert to previous "precise" image attribute"

This reverts commit 30a0d6ebb46b16389bf3f1ab71700346d78e1320.
Revert "Merge pull request #181 from cloudnull/BUG649"

This reverts commit 45c3dca5fb412e283dce3cf20259848528a79199, reversing
changes made to 83eeb202208a04cfb7d78ddf3d07b883f276d213.
Glance clients do version negotiation now.

Endpoint should not have a version.