liquibase.properties not being added if not already present

[kilna]

Derived images work fine, but volume-mounted changelog dirs typically don't have a liquibase.properties file in them, so it fails with an error.

See: https://github.com/kilna/liquibase-postgres-docker/issues/7

[thoroc]

Could it be as simple as replacing line 36 of the bin/entrypoint.sh file by the following?

  if [ -f "$PROPERTY_FILE" ]; then
    varsubst -x LIQUIBASE_ -s $opts $PROPERTY_FILE
  else
    printenv | grep LIQUIBASE_ >> $PROPERTY_FILE
  fi

having stored "liquibase.properties" as a local variable PROPERTY_FILE="liquibase.properties"