The Milwaukee Brewers couldn't finish off a weekend sweep of the Minnesota Twins at Target Field, falling 5-4 in a 15 inning marathon on Sunday.   The Brewers led 4-1 in the 5th when Corey Hart launched a three run homer.  In the 7th, starter Zack Greinke walked the leadoff man, got the next two outs, but surrendured four consecutive hits to allow the Twins to tie the game.  It went to the bullpens from there with both teams making fine defensive plays to extend the game.  In the bottom of the 15th, Tim Dillard let a couple of runners on and Dennard Spann's fourth hit of the game was a two out, walk off RBI single to give the home side the victory.   The Brewers (30-36) fall 8 1/2 games behind the Reds in the NL Central and return home to Miller Park to continue interleague play with a three game series against the Toronto Blue Jays.  Randy Wolf will pitch the series opener for the Brewers Monday night.