Remove unneeded middleware from server

`express.bodyParser()` is deprecated in the upcoming Connect version 3.0:

    connect.multipart() will be removed in connect 3.0
    visit https://github.com/senchalabs/connect/wiki/Connect-3.0 for alternatives

As hexo should only generate static files (and the server module isn't considered to run in a production environment), it should be safe to remove it completely along with `express.methodOverride()`.