Fix certain bugs

Dockerfile

@@ -34,13 +34,13 @@ RUN addgroup --gid 1000 seafile && \
     adduser --gid 1000 --uid 1000 --system --shell /bin/bash --home /haiwen seafile
 USER seafile
 # set environment variables for locale
-ARG LANG=C.UTF-8
-ARG LANGUAGE=C.UTF-8
-ARG LC_ALL=C.UTF-8
+ENV LANG=C.UTF-8
+ENV LANGUAGE=C.UTF-8
+ENV LC_ALL=C.UTF-8
 
 # set environment variables for seafile
-ARG ROOTPATH=/haiwen
-ARG INSTALLPATH=$ROOTPATH/seafile-server-latest
+ENV ROOTPATH=/haiwen
+ENV INSTALLPATH=$ROOTPATH/seafile-server-latest
 
 ENV CCNET_CONF_DIR=$ROOTPATH/ccnet
 ENV SEAFILE_CENTRAL_CONF_DIR=$ROOTPATH/conf

src/setenv.sh

-export PYTHONPATH=${INSTALLPATH}/seafile/lib/python2.7/site-packages:${INSTALLPATH}/seafile/lib64/python2.7/site-packages:${INSTALLPATH}/seahub/thirdpart:$PYTHONPATH
+export PYTHONPATH=${INSTALLPATH}/seafile/lib/python3.6/site-packages:${INSTALLPATH}/seafile/lib64/python3.6/site-packages:${INSTALLPATH}/seahub/thirdpart:$PYTHONPATH