add distillery based mix app class
add distillery based mix app class

  * new distillery based app class added that support building of
    elixir applications using mix and distillery release packager.
  * use lager-journald-backend as application dependency in prod mode
    and not in yocto layer.

carosio/meta-caros,wfailla/meta-caros,wfailla/meta-caros,wfailla/meta-caros,carosio/meta-caros,carosio/meta-caros,wfailla/meta-caros,umatomba/meta-caros,hsychla/meta-caros,hsychla/meta-caros,hsychla/meta-caros,umatomba/meta-caros,umatomba/meta-caros,wfailla/meta-caros,carosio/meta-caros,hsychla/meta-caros,carosio/meta-caros,hsychla/meta-caros,umatomba/meta-caros,umatomba/meta-caros