config: local addons modules should be loaded first

config: local addons modules should be loaded first

ifupdown2 can be installed via apt/dpkg or via pypi (pip), those two installation methods have
two different installation directory. Our main installation dir is /usr/share/ifupdown2. This is
also were other scripts might add their own addon.
If ifupdown2 is installed via pypi we need to make sure we are loading the script-added addon modules

Signed-off-by: Julien Fortin <julien@cumulusnetworks.com>