Add Dockerfile to simplify installation

Dockerfile

@@ -0,0 +1,13 @@
+FROM python:3.4-alpine
+WORKDIR /app
+COPY ./images /app/images
+COPY ./libgrabsite /app/libgrabsite
+COPY ./grab-site ./gs-dump-urls ./gs-server ./setup.py /app/
+RUN apk add --update build-base libffi-dev && \
+    pip3 install ./ && \
+    apk del --purge build-base libffi-dev && \
+    rm -R /root/.cache
+VOLUME ["/data"]
+WORKDIR /data
+EXPOSE 29000
+CMD ["python", "/app/gs-server"]

README.md

@@ -34,6 +34,7 @@ Note: grab-site currently **does not work with Python 3.5**; please use Python 3
 <!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
 **Contents**
 
+- [Install with Docker](#install-with-docker)
 - [Install on Ubuntu 14.04 - 15.10](#install-on-ubuntu-1404---1510)
 - [Install on Ubuntu 16.04](#install-on-ubuntu-1604)
 - [Install on a non-Ubuntu distribution lacking Python 3.4.x](#install-on-a-non-ubuntu-distribution-lacking-python-34x)
@@ -55,6 +56,27 @@ Note: grab-site currently **does not work with Python 3.5**; please use Python 3
 
 <!-- END doctoc generated TOC please keep comment here to allow auto update -->
 
+Install with Docker
+---
+After [installing Docker](https://docs.docker.com/engine/installation/), get the pre-built container:
+
+```bash
+docker pull slang800/grab-site
+```
+
+Start the grab-site server. You can set the port, volume, and name to whatever you want:
+
+```bash
+docker run --detach -p 29000:29000 -v ~/grabs:/data --name warcfactory slang800/grab-site
+```
+
+Run a new crawl:
+
+```bash
+docker exec warcfactory grab-site --no-offsite-links --1 http://xkcd.com/
+```
+
+The downloaded data, temp files, ignores list, and other configuration will be in a sub-directory of the mounted volume. In this case, `~/grabs/xkcd.com-2016-09-05-caf0a39c`.
 
 Install on Ubuntu 14.04 - 15.10
 ---