ensure installed is false when running installer

Dockerfile

@@ -19,6 +19,7 @@ RUN apk add --no-cache  \
     php7-json \
     php7-xml \
     php7-xmlreader \
+    php7-xmlwriter \
     php7-zlib \
     php7-zip \
     php7-pgsql \
@@ -33,7 +34,8 @@ RUN apk add --no-cache  \
     php7-bz2 \
     php7-exif \
     php7-apcu \
-    php7-ldap
+    php7-ldap \
+    php7-simplexml
 
 RUN mkdir /var/lib/nextcloud
 RUN wget -qO- https://download.nextcloud.com/server/releases/nextcloud-$VERSION.tar.bz2 | tar xj -C /var/lib/nextcloud --strip 1