Add dockerisation of server

Dockerfile

+FROM debian:9
+MAINTAINER Yoann Houpert <yhoupert@linagora.com>
+
+RUN apt-get update &&\
+    apt-get install -y \
+    sox \
+    python2.7 \
+    python-pip &&\
+    apt-get clean
+
+ENV BASE_DIR /opt/speech-to-text
+
+WORKDIR $BASE_DIR
+
+COPY . .
+COPY modules/server/server.cfg .
+RUN pip install -r modules/server/requirements.txt
+
+EXPOSE 8888
+
+CMD ./modules/server/master_server.py