build: force rebar to build 'setup' app

There is a bug in exometer/priv/check_packages.script: rebar doesn't build mandatory dependencies of exometer. We can workaround it adding +setup to EXOMETER_PACKAGES environment variable.
(cherry picked from commit 269c8649084d4f3dedf4bf4c3b223b7d63eb8248)

(cherry picked from commit 7d4ecb7a447e266df5bacf138c9c0af74b44a8d4)