[FIX]Odoo 8 on C7 : needs to trust pypi hosts

odoo/odoo/Dockerfile.8.centos7

@@ -26,7 +26,7 @@ WORKDIR /opt/odoo
 USER odoo
 RUN mkdir pipcache data backups extra-addons custom-addons && \
       git clone -b ${ODOO_BRANCH} --depth 1 https://github.com/OCA/OCB.git && \
-      pip install --user --no-cache-dir -r OCB/requirements.txt
+      pip install --trusted-host pypi.org --trusted-host pypi.python.org --trusted-host files.pythonhosted.org --user --no-cache-dir -r OCB/requirements.txt
 
 # Launch scripts
 COPY ./launch.sh ./launch.sh