Land #8898, move Dockerfile for publishing

Dockerfile

@@ -36,6 +36,7 @@ RUN apk update && \
       ncurses-dev \
       git \
     && echo "gem: --no-ri --no-rdoc" > /etc/gemrc \
+    && gem update --system \
     && gem install bundler \
     && bundle install --system $BUNDLER_ARGS \
     && apk del .ruby-builddeps \

docker-compose.yml

@@ -4,7 +4,7 @@ services:
     image: metasploit
     build:
       context: .
-      dockerfile: ./docker/Dockerfile
+      dockerfile: ./Dockerfile
     environment:
       DATABASE_URL: postgres://postgres@db:5432/msf
     links: