Updates path to autoload.php

[svperfecta]

When loaded with composer, bin symlinks are setup in vendor/bin (where vendor can be changed based on composers config.) Thus, I think we want to load autoload.php relative to the location of the bin symlink. We also don't want to reference the vendor folder itself.

[CHH]

Maybe we could do it in a similar way as Composer, which includes either the local autoloader in ../vendor when the library is checked out standalone or uses the autoloader of the project it's installed in.

This way the users can choose to checkout only Pipe when they just want to use pipe-server or pipe-compile.

See https://github.com/composer/composer/blob/master/src/bootstrap.php in composer for some guidance.

[CHH]

BTW, the build is not really failing for this change — it's just Travis having some issues apparently.

[svperfecta]

Good idea. I'll take a look at this today.

[svperfecta]

Try this @chh. Should take care of it.

[CHH]

Thanks!