Migrate flowable from in-memory DB to file DB

The default in-memory DB is making the OSOM container continuously grow in terms of memory potentially reaching the host machine limits.

The transition to file DB will take up the same size, but on disk.

Once the container is destroyed the file DB will get killed, freeing up space.

assigned to @ktrantzas

marked this issue as blocking #19 (closed)

marked this issue as related to org.etsi.osl.main#27 (closed)

closed

added typeenhancement label