Update to checkout process fields

[josh-padnick]

The current checkout process asks for minimal identifying information from the customer:

The issue here is that we need to be crystal clear on the corporate entity with whom we have a contract. For that reason, we need to add more identifying information. In particular, this screen should make the following changes:

1. "Company name" should be updated to say "Company legal entity name" (and should be required)
2. We should add "Company legal address" (and should be required)

Note that you can make these changes by logging into our ChargeBee account.

@oredavids Can you prioritize this above all current items on your plate?