Allow passing multiple parameters to app.use()

[babolivier]

I just found myself in a case where I have to serve multiple static directories, each with a different path. Express's documentation tells us this can be done by passing the path as the first app.use() parameter:

app.use('/static', express.static('public'))

This PR allows Americano's config to do just this. If a path must be added to the static directory, the use configuration shall look like this:

use: [
    americano.bodyParser(),
    americano.methodOverride(),
    americano.static(__dirname + '/../../client/public', {
        maxAge: 86400000
    }),
    ['/static', americano.static(__dirname + '/../../testStatic', {
        maxAge: 86400000
    })]
]

In this example you can see how my client/public directory is being served statically without a path (so using the root), and my testStatic directory is being served statically on /static.