make boot.sh run as process 0

we want boot.sh to correctly receive and forwards signals. this commit removes
the double indirection (`CMD` in non array form will already execute the command
in a sh subshell and we wrapped our script in another one).

Author: nvdk

Dockerfile

@@ -24,7 +24,7 @@ RUN chmod +x /usr/src/app/build-production.sh
 
 EXPOSE ${PORT}
 
-CMD sh boot.sh
+CMD ["/usr/src/app/boot.sh"]
 
 # This stuff only runs when building an image from the template
 ONBUILD RUN rm -Rf /app/scripts

boot.sh

@@ -1,3 +1,4 @@
+#!/usr/bin/env bash
 if [ "$NODE_ENV" == "development" ]
 then
     # Run live-reload development