plugin app manager docker: use default emails for weblate: when `email_from` was not set in `sat.conf`, no value was set for `WEBLATE_SERVER_EMAIL` and `WEBLATE_DEFAULT_FROM_EMAIL`. These environment variables are needed for Weblate to be launched, so default value are now used (the same as the one from official Weblate Docker image).

# XXX: the Monkey Patch is here and not in src/__init__ to avoir issues with pyjamas compilation
# TODO: remove this when changes are merged in Wokkel
from sat_tmp.wokkel import install
install()