🔧(dogwood.3-fun) add a pip.conf file to trust a list of domain

Since end of april, pypi has renew the certificates of a list domain
used by pip to install dependencies. Those certificates are not
recognized anymore by our version of ubuntu. To fix this issue, we have
to trust a restricted list of domain present in the pip.conf file

Author: lunika

releases/dogwood/3/fun/Dockerfile

@@ -179,6 +179,7 @@ RUN pip install -r requirements/edx/pre.txt
 # Splinter is a sub-dependency. The version match pattern is >=0.5.0
 # but the version 0.17.0 dropped the support for Python 2.7 we install manually the
 # latest compatible version to prevent the installation of 0.17.0.
+COPY pip.conf /etc/pip.conf
 RUN pip install \
     pip==9.0.3 \
     urllib3==1 \

releases/dogwood/3/fun/pip.conf

@@ -0,0 +1,4 @@
+[global]
+trusted-host = pypi.python.org
+               pypi.org
+               files.pythonhosted.org