Fix missing API docs

See https://github.com/openlayers/ol3/pull/2479#issuecomment-51438681.

Removes attribution#tileRanges as suggested, and adds `@api` for others. Two are not addressed here: `ol.format.Feature` and `ol.render.IVectorContext`. These are parent classes, already in the api docs, and AFAICS are only referred to as types in private methods. I'm not sure what needs to be done here - should they be template types (`T`)?
The `ol.format.WFS.TransactionResponse` actually just serves the purpose of ducumenting what's returned by the `readTransactionResponse` function. The `readTransactionResponse` function uses `goog.object.set` to set properties on the object, which means what's documented with the typedef is effectively what the user will get. 

The `ol.format.WFS.FeatureColllectionMetadata` type plays a similar role – it documents what's returned by the `readFeatureCollectionMetadata` function.

So I think annotating these typedef's with `@api` does not cause any harm.

One thing to note though is that the object returned by `ol.format.WMSCapabilities#read` is not documented – there's no `typedef` for it. A `typedef` for that object would be much more complex than `TransactionResponse` and `FeatureColllectionMetadata`.