By treating the apps in the umbrella as dependencies to be managed and
built by rebar3, we can simplify the maintenance of the release, at
the cost of increased build times: using Mix as before, it could track
changed files better than using rebar. But the complexity and
possibility of discrepancies make it using rebar much more compelling.
* chore(conf): add quotation for hocon
* chore(conf): fix paths incompatible with hocon
* chore(conf): use hocon as parsing function
* chore(docker): add quotation to some env variables for hocon