feat(web-ui): add transmission-web-control UI

This is based upon the project https://github.com/ronggang/transmission-web-control/

Dockerfile

     && wget https://github.com/Secretmapper/combustion/archive/release.zip \
     && unzip release.zip -d /opt/transmission-ui/ \
     && rm release.zip \
+    && wget https://github.com/ronggang/twc-release/raw/master/src.tar.gz \
+    && mkdir /opt/transmission-ui/transmission-web-control \
+    && tar -xvf src.tar.gz -C /opt/transmission-ui/transmission-web-control/ \
+    && rm src.tar.gz \
     && git clone git://github.com/endor/kettu.git /opt/transmission-ui/kettu \
     && apt-get install -y tinyproxy telnet \
     && wget https://github.com/Yelp/dumb-init/releases/download/v1.2.0/dumb-init_1.2.0_amd64.deb \

Dockerfile.alpine

     && echo "Install kettu" \
     && wget -qO- https://github.com/endor/kettu/archive/master.tar.gz | tar xz -C /opt/transmission-ui \
     && mv /opt/transmission-ui/kettu-master /opt/transmission-ui/kettu \
+    && echo "Install Transmission-Web-Control" \
+    && mkdir /opt/transmission-ui/transmission-web-control
+    && wget -q0- https://github.com/ronggang/twc-release/raw/master/src.tar.gz | tar xz -C /opt/transmission-ui/transmission-web-control \
     && rm -rf /tmp/* /var/tmp/* \
     && groupmod -g 1000 users \
     && useradd -u 911 -U -d /config -s /bin/false abc \

Dockerfile.armhf

     && unzip release.zip -d /opt/transmission-ui/ \
     && rm release.zip \
     && git clone git://github.com/endor/kettu.git /opt/transmission-ui/kettu \
+    && wget https://github.com/ronggang/twc-release/raw/master/src.tar.gz \
+    && mkdir /opt/transmission-ui/transmission-web-control \
+    && tar -xvf src.tar.gz -C /opt/transmission-ui/transmission-web-control/ \
+    && rm src.tar.gz \
     && apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/* \
     && curl -L https://github.com/jwilder/dockerize/releases/download/v0.6.0/dockerize-linux-armhf-v0.6.0.tar.gz | tar -C /usr/local/bin -xzv \
     && groupmod -g 1000 users \

README.md

 ### Alternative web UIs
 You can override the default web UI by setting the ```TRANSMISSION_WEB_HOME``` environment variable. If set, Transmission will look there for the Web Interface files, such as the javascript, html, and graphics files.
 
-[Combustion UI](https://github.com/Secretmapper/combustion) and [Kettu](https://github.com/endor/kettu) come bundled with the container. You can enable either of them by setting```TRANSMISSION_WEB_UI=combustion``` or ```TRANSMISSION_WEB_UI=kettu```, respectively. Note that this will override the ```TRANSMISSION_WEB_HOME``` variable if set.
+[Combustion UI](https://github.com/Secretmapper/combustion), [Kettu](https://github.com/endor/kettu) and [Transmission-Web-Control](https://github.com/ronggang/transmission-web-control/) come bundled with the container. You can enable either of them by setting```TRANSMISSION_WEB_UI=combustion```, ```TRANSMISSION_WEB_UI=kettu``` or ```TRANSMISSION_WEB_UI=transmission-web-control```, respectively. Note that this will override the ```TRANSMISSION_WEB_HOME``` variable if set.
 
 | Variable | Function | Example |
 |----------|----------|-------|
 |`TRANSMISSION_WEB_HOME` | Set Transmission web home | `TRANSMISSION_WEB_HOME=/path/to/web/ui`|
-|`TRANSMISSION_WEB_UI` | Use the specified bundled web UI | `TRANSMISSION_WEB_UI=combustion` or `TRANSMISSION_WEB_UI=kettu`|
+|`TRANSMISSION_WEB_UI` | Use the specified bundled web UI | `TRANSMISSION_WEB_UI=combustion`, `TRANSMISSION_WEB_UI=kettu` or `TRANSMISSION_WEB_UI=transmission-web-control`|
 
 ### Transmission configuration options
 

transmission/start.sh

   export TRANSMISSION_WEB_HOME=/opt/transmission-ui/kettu
 fi
 
+if [ "transmission-web-control" = "$TRANSMISSION_WEB_UI" ]; then
+  echo "Using Transmission Web Control  UI, overriding TRANSMISSION_WEB_HOME"
+  export TRANSMISSION_WEB_HOME=/opt/transmission-ui/transmission-web-control
+fi
+
 echo "Generating transmission settings.json from env variables"
 # Ensure TRANSMISSION_HOME is created
 mkdir -p ${TRANSMISSION_HOME}