Revisit check_up_to_date for nmboot models

[barrettk]

A check_up_to_date was recently implemented in #687 (see method). There are couple implementation details we are considering changing:

• This call aborts if the model has not been submitted. Due to the unique nature of bootstrap runs, this is not actually necessary. In other words you could check if the model was up-to-date before submitting the model if we removed this abort call. This is because we hash the based_on_data and model during the setup phase, rather than the submission. We are considering removing this abort call
• Add a check_up_to_date call in submit_model.bbi_nmboot_model

[barrettk]

FWIW this is not an issue that needs to be addressed before we release the new bootstrap feature