package.default.json has moved

https://github.com/NodeBB/NodeBB/commit/eb47a81c46b9a457cefd52026831babcdb0238bf

Dockerfile

@@ -8,7 +8,7 @@ ENV PATH /usr/local/node-6.9.5/bin:$PATH
 
 RUN curl -L https://github.com/NodeBB/NodeBB/archive/v1.7.1.tar.gz | tar -xz --strip-components 1 -f -
 ADD config.json.template /app/code
-RUN cp /app/code/package.default.json /app/code/package.json
+RUN cp /app/code/install/package.json /app/code/package.json
 RUN npm install --production
 RUN npm install nodebb-plugin-emailer-local