Clean up and volume for oradata

Remove obsolete port and expose `/usr/lib/oracle/xe/oradata/XE` as a VOLUME.

Author: alexei-led

Dockerfile

@@ -23,7 +23,8 @@ RUN echo 'export ORACLE_HOME=/u01/app/oracle/product/11.2.0/xe' >> /etc/bash.bas
 RUN echo 'export PATH=$ORACLE_HOME/bin:$PATH' >> /etc/bash.bashrc
 RUN echo 'export ORACLE_SID=XE' >> /etc/bash.bashrc
 
-EXPOSE 22
+VOLUME /usr/lib/oracle/xe/oradata/XE
+
 EXPOSE 1521
 EXPOSE 8080