OPSK-1768 updated Docker build to use Ruby 2.4 base image
OPSK-1768 updated Docker build to use Ruby 2.4 base image

ruby 2.4 is now the supported version, and also the newer container
avoids the need to backport for Java 8

needed to setup locales for UTF-8 to get rmagick (and potentially other gems) to
install successfully.

HITS-SDBV/seek,HITS-SDBV/seek,HITS-SDBV/seek,HITS-SDBV/seek