use unsafe-perm when building dat since we are root

Dockerfile

@@ -1,7 +1,7 @@
 FROM mafintosh/docker-adventure-time
 RUN apt-get install -qy docker.io libncurses5-dev
 RUN npm install -g docker-run@1.3.0 bionode-sam@1.0.1 bionode-ncbi@1.0.2 bionode-sra@1.0.1 bionode-bwa@0.0.9
-RUN npm install -g dat@7.0.0-pre-3
+RUN npm install -g --unsafe-perm dat@7.0.0-pre-3
 RUN npm install -g tool-stream gasket mafintosh/picture-tube#patch-1 serve json flatsheet
 RUN mkdir -p /pictures
 ADD welcome.txt /