Dockerfile builds from source

Uses multi-stage build, like jfa-go. I'm hoping this'll shrink the image
aswell.

Dockerfile

@@ -0,0 +1,27 @@
+FROM python:3.8.2-buster AS build
+
+COPY . /opt/build
+
+RUN curl -sSL https://raw.githubusercontent.com/python-poetry/poetry/master/get-poetry.py | python
+
+RUN curl -sL https://deb.nodesource.com/setup_14.x | bash -
+
+RUN cd /opt/build \
+    && rm -rf dist \
+    && apt install nodejs \
+    && ~/.poetry/bin/poetry update \
+    && pip install libsass \
+    && python scss/get_node_deps.py \
+    && python scss/compile.py -y \
+    && python mail/generate.py -y \
+    && ~/.poetry/bin/poetry build -f wheel
+
+FROM python:3.8.2-buster
+
+COPY --from=build /opt/build/dist /opt/dist
+
+RUN pip install /opt/dist/*.whl
+
+RUN sed -i 's#id="pwrJfPath" placeholder="Folder"#id="pwrJfPath" value="/jf" disabled#g' /usr/local/lib/python3.8/site-packages/jellyfin_accounts/data/templates/setup.html
+
+CMD [ "python3.8", "/usr/local/bin/jf-accounts", "-d", "/data" ]