Customers: Add proposed business customer type fields

[darwinz]

This is a sub-task of the epic to support business profiles.

Proposed work

Add the following fields to the customer model to support business profiles

• Customer type: business (exists today)
• Business name
• Doing business as (optional)
• Business type
  • Individual, sole proprietor, or single-member LLC
  • Corporation
  • Nonprofit organization
  • Partnership
  • Limited liability company
• Addresses (already exists)
• Phone numbers (already exists)
• SIC code (optional)
  Business Classification & Tags | SIC Codes - Google docs
• NAICS code (optional)
  Business Classification & Tags | NAICS Codes - Google docs
• Website (optional)
• Email Address (already exists)
• EIN (optional)
• Date established (optional)
• D&B D-U-N-S number (optional)
• Representatives (optional array)
  • First name
  • Last name
  • Job title
  • Date of birth
  • SSN (last 4)
  • Addresses
  • Phone numbers
  • Email address

[adamdecaf]

@darwinz can we create a PR of just the models being added? I want to agree on the descriptions, naming, etc before merging. With so many models I want @joshsadler and folks to be on the same page.

Also, can we hold off merging this until v0.5.0 is released? I don't want to introduce partial support for businesses right now.