Don't VERIFY_NONE when VERIFY_PEER is requested

Looks like a5e9485d inverted the logic on this, which seems pretty bad.

This reversal of the explicit setting only affects Typhoeus, as far as I can tell. 

Other SSL issues I noticed and could address as part of this PR or a different one: 
- The [EMHttp adapter](https://github.com/lostisland/faraday/blob/master/lib/faraday/adapter/em_http.rb#L36-L43) doesn't appear to apply any SSL settings at all.
- The [Net::HTTP adapter](https://github.com/lostisland/faraday/blob/master/lib/faraday/adapter/net_http.rb#L108-L116) uses `VERIFY_PEER` by default, but the [HTTPClient adapter](https://github.com/lostisland/faraday/blob/master/lib/faraday/adapter/httpclient.rb#L81-L89) uses `VERIFY_PEER | VERIFY_FAIL_IF_NO_PEER_CERT`

I'm also seeing some intermittent test failures, but they don't seem to pass any more or less based on this change.