Remove BFGMiner link because of malware warning on Chrome

[i-rme]

Remove BFGMiner link because of malware warning on Chrome

[luke-jr]

NACK. That's a bug with Chrome, there is no actual malware.

See https://bugs.chromium.org/p/chromium/issues/detail?id=672984

[wbnns]

@luke-jr Thanks for the note about Chrome. It looks like this is also happening in Safari and Firefox.

Safari Version 10.0.1 (12602.2.14.0.7):

Firefox 50.1.0:

Is there a URL that this can be replaced with (instead of removing the link altogether as this PR suggests) until the issue is resolved?

[i-rme]

@wbnns
The webpage redirects to https://bitcointalk.org/?topic=877081

It might be a good replacement link although the download links still links to a website flagged as malware.

[crwatkins]

NACK. This is just a detection signature problem. Extremely unfortunate, but there's nothing to be gained by removing our link. Good luck @luke-jr getting them to fix it.

[wbnns]

Unless others object, this will not be merged and the pull request will be closed on Sunday, December 25th.

@i-rme @luke-jr @crwatkins Thank you all for the feedback.