Add possibility to use an intermediate dir

Dockerfile

@@ -76,8 +76,10 @@ RUN chmod 644 /usr/local/share/tessdata/*.traineddata
 ## Install Pipeline ##
 RUN apt-get install -y --no-install-recommends \
       ghostscript \
+      python-pip \
       python3.7 \
-      zip
+      zip \
+ && pip install natsort
 COPY "hocrtotei" "ocr" "/usr/local/bin/"