also installing zip and unzip. issue #75

Dockerfile

@@ -15,7 +15,7 @@ RUN apt-get update \
     && add-apt-repository ppa:transmissionbt/ppa \
     && apt-get update \
     && apt-get install -y transmission-cli transmission-common transmission-daemon \
-    && apt-get install -y openvpn curl rar unrar \
+    && apt-get install -y openvpn curl rar unrar zip unzip \
     && apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/* \
     && curl -L https://github.com/jwilder/dockerize/releases/download/v0.0.2/dockerize-linux-amd64-v0.0.2.tar.gz | tar -C /usr/local/bin -xzv