Local changes until upstream patching to support eduID IdP

The current pyFF code base cannot return metadata for the eduID IdP when
requested by the Shibboleth IdP. See GitHub issue
IdentityPython/pyFF#193
and related Shibboleth SP issue
https://issues.shibboleth.net/jira/browse/SSPCPP-887
This commit adds a simple local patch to workaround the issue
for now.

Dockerfile

@@ -4,8 +4,8 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
         supervisor \
         virtualenv
 
-# Until PR 192 is merged use a special source URL.
-ENV PYFF_SRC_URL=git+https://github.com/IdentityPython/pyFF.git@refs/pull/192/merge
+# Use a particular commit:
+ENV PYFF_SRC_URL=git+https://github.com/IdentityPython/pyFF.git@7705880df77538f5d34976da5e26db1f80a75e53
 
 RUN mkdir -p /opt/pyff \
     && adduser --home /opt/pyff --no-create-home --system pyff --group \
@@ -15,6 +15,14 @@ RUN mkdir -p /opt/pyff \
     && pip install ${PYFF_SRC_URL} \
     && chown -R pyff:pyff /opt/pyff
 
+# Until Issue 193
+#
+# https://github.com/IdentityPython/pyFF/issues/193
+#
+# is resolved or the Shibboleth SP changes what it sends
+# in the Accept header monkey patch.
+COPY api.py /opt/pyff/lib/python3.7/site-packages/pyff/api.py
+
 COPY supervisord.conf /usr/local/etc/supervisord.conf
 COPY pyff-start.sh /usr/local/bin/pyff-start.sh
 COPY gunicorn_sighup.py /opt/pyff/gunicorn_sighup.py