Make Tor optional in the Docker image and disable it by default as it's usage may be not allowed by hosting providers

Dockerfile

@@ -21,8 +21,11 @@ RUN \
 ADD . /root
 VOLUME /root/data
 
+#Control if Tor proxy is started
+ENV ENABLE_TOR false
+
 #Set upstart command
-CMD cd /root && /etc/init.d/tor start && python zeronet.py --ui_ip 0.0.0.0
+CMD cd /root && (! ${ENABLE_TOR} || /etc/init.d/tor start) && python zeronet.py --ui_ip 0.0.0.0
 
 #Expose ports
 EXPOSE 43110

README.md

@@ -103,6 +103,11 @@ It downloads the latest version of ZeroNet then starts it automatically.
 
 ### [Docker](https://www.docker.com/)
 * `docker run -d -v <local_data_folder>:/root/data -p 15441:15441 -p 43110:43110 nofish/zeronet`
+* This Docker image includes the Tor proxy, which is disabled by default. Beware that some
+hosting providers may not allow you running Tor in their servers. If you want to enable it,
+set `ENABLE_TOR` environment variable to `true` (Default: `false`). E.g.:
+
+ `docker run -d -e "ENABLE_TOR=true" -v <local_data_folder>:/root/data -p 15441:15441 -p 43110:43110 nofish/zeronet`
 * Open http://127.0.0.1:43110/ in your browser
 
 ### [Virtualenv](https://virtualenv.readthedocs.org/en/latest/)