* Support Metadata in GridFSAdapter
* Useful for testing in the JS SDK
* Adds new endpoint to be used with `Parse.File.getData`
* Allows file adapters to return tags as well as future data.
* fix tests
* Make getMetadata optional
* Revert "fix tests"
This reverts commit 7706da13c688027483974e854b5b24321fb070cd.
* improve coverage