Merge pull request #17 from hackmdio/update/node

Update node to version 8.15.0

alpine/Dockerfile

-FROM node:8.12.0-alpine
+FROM node:8.15.0-alpine
 
 # Build arguments to change source url, branch or tag
 ARG CODIMD_REPOSITORY=https://github.com/hackmdio/codimd.git

debian/Dockerfile

-FROM node:8.12.0
+FROM node:8.15.0
 
 # Build arguments to change source url, branch or tag
 ARG CODIMD_REPOSITORY=https://github.com/hackmdio/codimd.git
@@ -22,7 +22,7 @@ RUN set -ex; \
     \
 # verify the signature
     export GNUPGHOME="$(mktemp -d)"; \
-    gpg --import /tmp/gosu.key; \
+    gpg --no-tty --import /tmp/gosu.key; \
     gpg --batch --verify /usr/local/bin/gosu.asc /usr/local/bin/gosu; \
     rm -rf "$GNUPGHOME" /usr/local/bin/gosu.asc; \
     \