Update Dockerfile

It will use WORKDIR instead of cd /opt

Dockerfile

@@ -31,15 +31,16 @@ RUN apt-get update && apt-get install -y  \
     pip install tornado && \    
     ln -s /usr/bin/python2.7 /usr/bin/python ; ln -s -f bash /bin/sh
 
-RUN cd /opt && wget http://www.digip.org/jansson/releases/jansson-2.7.tar.bz2 && \
+WORKDIR /opt
+
+RUN wget http://www.digip.org/jansson/releases/jansson-2.7.tar.bz2 && \
     bunzip2 -c jansson-2.7.tar.bz2 | tar xf -  && \
     cd jansson-2.7 && \
     ./configure && make && make check &&  make install && \
     echo "/usr/local/lib" >> /etc/ld.so.conf.d/jansson.conf && ldconfig && \
     rm /opt/jansson-2.7.tar.bz2 && rm -rf /opt/jansson-2.7
 
-RUN cd /opt && \
-    git clone https://github.com/kaldi-asr/kaldi && \
+RUN git clone https://github.com/kaldi-asr/kaldi && \
     cd /opt/kaldi/tools && \
     make && \
     ./install_portaudio.sh && \