feat(docker): Run API processes using pelias user

This is enabled by the work in https://github.com/pelias/baseimage/pull/2 and lets us ensure the API is run as
a non-root user.

Additionally the maintainer label is now set in the baseimage as of
(https://github.com/pelias/baseimage/pull/8), so it can be removed here.

Dockerfile

@@ -1,11 +1,7 @@
 # base image
 FROM pelias/baseimage
-RUN useradd -ms /bin/bash pelias
 USER pelias
 
-# maintainer information
-LABEL maintainer="pelias.team@gmail.com"
-
 # Where the app is built and run inside the docker fs
 ENV WORK=/home/pelias
 WORKDIR ${WORK}