Add test & spec folder to docker container

It would have been nicer to also exclude the test and spec folder within
the production container, saving some space within that, but the docker
COPY statement doesn't allow for that without a workaround. So this is
what we will do for now I guess.

.dockerignore

@@ -1,6 +1,4 @@
 .git
-test/**
-spec/**
 tmp/**
 .gitignore
 .hound.yml