Add Mac compatibility to boulder-start

The version of sort that ships with OS X does not support the -V
version flag. Emulate that functionality with some sed-fu

tests/boulder-start.sh

@@ -8,7 +8,12 @@ GOVER=`go version | cut -d" " -f3 | cut -do -f2`
 
 # version comparison
 function verlte {
+  if [ `uname` == 'Darwin' ]; then
+    [ "$1" = "`echo -e \"$1\n$2\" |  sed 's/\b\([0-9]\)\b/0\1/g' \
+      | sort | sed 's/\b0\([0-9]\)/\1/g' | head -n1`" ]
+  else
     [  "$1" = "`echo -e "$1\n$2" | sort -V | head -n1`" ]
+  fi
 }
 
 if ! verlte 1.5 "$GOVER" ; then