Move vint to Docker

Dockerfile

@@ -5,9 +5,13 @@ RUN install_vim -tag v8.0.0000 -build \
 
 ENV PACKAGES="\
     git \
+    python=2.7.12-r0 \
+    py-pip=8.1.2-r0 \
 "
 RUN apk --update add $PACKAGES && \
     rm -rf /var/cache/apk/* /tmp/* /var/tmp/*
 
+RUN pip install vim-vint==0.3.9
+
 RUN git clone https://github.com/junegunn/vader.vim vader && \
     cd vader && git checkout c6243dd81c98350df4dec608fa972df98fa2a3af