Allow setting options before setting models

[sjudd]

Branching this out of a discussion in #179, it would be nice to be able to apply options to a builder and then use that single builder with those options to load multiple different models. Glide doesn't currently allow this because some options are type specific and currently the only way we know the available types is from the model we're given.

My solution for now has been to wrap load calls in a class that specifies options:

public class GlideManager {

    public GlideManger(Activity activity) {
        requestManager = Glide.with(activity);
    }

    public GlideManger(Fragment fragment) {
        requestManager = Glide.with(fragment)
    }

    public DrawableRequestBuilder<Uri> loadThumb(Uri uri) {
        return requestManager.load(uri)
            .centerCrop()
            ....
    }
}

Which is then used like this:

glideManager.loadThumb(myUri).drawable(R.drawable.spinner).into(myView);

Although this works, it would be more convenient to simply define a builder somewhere at the top of the Activity or fragment and call into repeatedly.