Introduce DOKKU_ROOT and import now in git plugin

plugins/git/backup-import

@@ -0,0 +1,17 @@
+#!/bin/bash
+VERSION="$1"
+IMPORT_DIR="$2"
+TARGET_DIR="$3"
+APPS="$4"
+
+while read APP; do 
+    APP_PATH="$TARGET_DIR/$APP"; 
+    git init --bare $APP_PATH > /dev/null
+    PRERECEIVE_HOOK="$APP_PATH/hooks/pre-receive"
+    cat > $PRERECEIVE_HOOK <<EOF
+#!/usr/bin/env bash
+set -e; set -o pipefail;
+cat | DOKKU_ROOT="$DOKKU_ROOT" dokku git-hook $APP
+EOF
+    chmod +x $PRERECEIVE_HOOK
+done < $APPS > /dev/null