Added sendfile support

[dknell]

There seems to be an issue in nginx on VirtualBox/Vagrant when sendfile is set to 'on'. This PR simply allows the user to override the default sendfile setting like this:

class { 'nginx': 
    sendfile             => 'off',
    proxy_http_version   => '1.1',
    proxy_set_header     => [
        'Upgrade $http_upgrade',
        'Connection "upgrade"',
        'Host $host'
    ]
}

[jfryman]

Dig it! Thanks for the code

[globin]

Any chances in getting this merged soonishly?

[jfryman]

I could have sworn I did. 😳

Taking care of that now.

[jfryman]

Aargh! Needs a rebase, @dbubs

[janorn]

This has now been added in #343