Fix refund calculation bug in BetaProgramInitiator (part 2)

[cygnusv]

(Continuation of #228)

As part of a longer-term solution that doesn't involve the Threshold Council and/or Treasury Guild managing refunds manually, this PR sets the refunds to be 100% so that the complete fee goes back to the BetaProgramInitiator, and then to the original adopter.

Type of PR:

• Bugfix
• Feature
• Documentation
• Other

Required reviews:

• 1
• 2
• 3

What this does:

High-level idea of the changes introduced in this PR.
List relevant API changes (if any), as well as related PRs and issues.

Issues fixed/closed:

• Fixes #...

Why it's needed:

Explain how this PR fits in the greater context of the NuCypher Network.
E.g., if this PR address a nucypher/productdev issue, let reviewers know!

Notes for reviewers:

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Is there a particular commit/function/section of your PR that requires more attention from reviewers?

[derekpierre]

🎸

(Already deployed and used on mainnet)