Add small business flag

[vdavez]

As an API consumer, I want to know whether a given business is a small business for any NAICS code so that I can determine whether they satisfy the small business requirements for a given solicitation.

As described here, there is value to having a simple flag of whether a business in SAM is a small business, and right now, it's super hard to do it without a bunch of logic. That logic, it seems to me, should be included in the samwise gem.