Consider refactoring license, cost, accessibility

[hansioan]

@matuskalas says these can be reduced and made clearer. Let's discuss here @joncison @hmenager

[joncison]

I propose:

• leave the definition of cost as it is - I don't see what's wrong with it.
• remove from accessibility the terms Proprietary and Freeware which conflate with license (see below) and confuse the meaning of accessibility quite badly. If we did this, accessibility simply becomes a choice between Open access and Restricted access (applicable to online services only) which is very clear
• leave License as it is. There is Proprietary, Unlicensed and Other but I think they all serve a purpose. PS. we've used "Unlicensed" quite a lot where we searched for a license, but one does not exist.

cc @hansioan @matuskalas @hmenager

[joncison]

Done in 3.2.0:

• removed from accessibility the terms Proprietary and Freeware
• added Freeware to License (to go alongside Proprietary which is already there

and updated the definitions

[joncison]

NB: cardinality set to 0 or 1 (was 0 to many) given there's now a choice between two mutually exclusive things.