normalise 'build' function args to match 'release' and 'deploy'

dokku

@@ -6,7 +6,7 @@ case "$1" in
   receive)
     APP="$2"; IMAGE="app/$APP"
     echo "-----> Building $APP ..."
-    cat | dokku build $IMAGE
+    cat | dokku build $APP $IMAGE
     echo "-----> Build complete!"
     echo "-----> Releasing $APP ..."
     dokku release $APP $IMAGE
@@ -23,10 +23,11 @@ case "$1" in
     ;;
 
   build)
-    IMAGE="$2"
+    APP="$2"; IMAGE="$3"
     id=$(cat | docker run -i -a stdin progrium/buildstep /bin/bash -c "mkdir -p /app && tar -xC /app")
     test $(docker wait $id) -eq 0
     docker commit $id $IMAGE > /dev/null
+    pluginhook pre-build $APP $IMAGE
     id=$(docker run -d $IMAGE /build/builder)
     docker attach $id
     test $(docker wait $id) -eq 0