add faraday connection options without breaking api

SSL options can only be passed to Faraday on initialization. So I've added a `connection_options` property which is passed to Faraday directly.

```ruby
Hyperclient.new('https://api.example.com/') do |client|
  client.connection_options = { ssl: { verify: false } }
  client.connection do |conn|
    conn.authorization :Bearer, 'ioP_pcKLhB4NLMGKMM6B40rwkBC.5o2JpsnBHhmKs4QAExG'
  end
end
```

I think it would be better if the options hash of `connection` would be passed to Faraday, then we can simply write:
```ruby
Hyperclient.new('https://api.example.com/') do |client|
  client.connection(ssl: { verify: false }) do |conn|
    conn.authorization :Bearer, 'ioP_pcKLhB4NLMGKMM6B40rwkBC.5o2JpsnBHhmKs4QAExG'
  end
end
```

But this means the use `options[:default]` should be changed to something like a property of the client, and thus breaking the API.