Vikings coach Brad Childress says running back Adrian Peterson is feeling as good as he’s felt all season.  That’s real encouraging since Peterson returned on Sunday from a knee injury that kept the rookie off the field for two weeks.  Peterson ran for 116-yards and two touchdowns in the win over the Lions, lengthening his lead as the NFL’s top rusher.  He’s wearing a brace on his right knee and plans to do so for the rest of the season.  The Vikings play at San Francisco on Sunday, and are tied for second place in the NFC wild card race following a three-game winning streak.