[FIX] Dockerfile fixed according to Yosifkit's review

- Clean up of APT with rm -rf /var/lib/apt/lists/*
  - Use environment variables for db_user and db_password
  - Install Odoo release of 12/31/2014

8.0/Dockerfile

@@ -15,7 +15,7 @@ RUN apt-get update \
         && echo '07d397b32f91722de683e8777df2ddd6c49662c2  wkhtmltox.deb' | sha1sum -c - \
         && dpkg --force-depends -i wkhtmltox.deb \
         && apt-get -y install -f \
-        && rm -f wkhtmltox.deb
+        && rm -rf /var/lib/apt/lists/* wkhtmltox.deb
 
 # Grab gosu for easy step-down from root
 RUN gpg --keyserver pgp.mit.edu --recv-keys B42F6819007F00F88E364FD4036A9C25BF357DD4
@@ -27,11 +27,12 @@ RUN curl -o /usr/local/bin/gosu -SL "https://github.com/tianon/gosu/releases/dow
 
 # Install Odoo
 ENV ODOO_VERSION 8.0
-ENV ODOO_RELEASE 20141229
+ENV ODOO_RELEASE 20141231
 RUN curl -o odoo.deb -SL http://nightly.odoo.com/${ODOO_VERSION}/nightly/deb/odoo_${ODOO_VERSION}.${ODOO_RELEASE}_all.deb \
         && dpkg --force-depends -i odoo.deb \
+        && apt-get update \
         && apt-get -y install -f --no-install-recommends \
-        && rm -f odoo.deb
+        && rm -rf /var/lib/apt/lists/* odoo.deb
 
 # Retrieve Odoo public key and add Odoo nightly to repo list for further updates
 RUN apt-key adv --keyserver pgp.mit.edu --recv-keys 0xdef2a2198183cbb5 \