Remove the Infrastructure Funding Plan from 15 May 2020 upgrade

This implements the IFP reversion which was requested and closed without proper procedure in https://github.com/bitcoincashorg/bitcoincash.org/pull/453 .

The funding part of the recently merged Github PR #444 did not have consensus and was added 18 days after feature freeze.

Maintainers of the bitcoincash.org repository have violated established procedure to not respect feature freeze and to include changes for which there is strong lack of consensus (in fact, there is very vocal disagreement from large parts of the community about the IFP and its implementation in an existing client).

The IFP feature is still incompletely specified with warning in the May upgrade spec on bitcoincash.org, and it is 3 weeks after the initial pull request to revert it.

No other well known client except Bitcoin ABC implemented the IFP, yet BCHN is being excluded from being listed on the site with reason given that it deviates from the specification which only ABC seems to want and has implemented without acceptable community consultation.