Avram::Database.transaction block return behavior undocumented and may be incorrect

[BrucePerens]

Avram::Database.transaction wants the transaction block to always return true. This is not documented, and is probably a left-over from when someone was designing how the user would roll back the transaction, perhaps returning false was considered for initiating a rollback. Obviously we have Avram::Database.rollback to do that today, so the transaction block should have its return value ignored.

[BrucePerens]

The problem still exists. Avram::Database#transaction wants the transaction block to return true here.

# :nodoc:
  def transaction : Bool
    if current_transaction
      yield
    else
      wrap_in_transaction do
        yield
      end
    end
  end

[matthewmcgarvey]

While I think we could work around it, this stems from the crystal-db library crystal-lang/crystal-db#145