getBlobMetadata = function(id) {
            var params = paramsStore.get(id);
            params[filenameParam] = getName(id);
            return params;
        }
Upload handler used by the upload to Azure module that depends on File API support, and, therefore, makes use of
`XMLHttpRequest` level 2 to upload `File`s and `Blob`s directly to Azure Blob Storage containers via the
associated Azure API.

@param spec Options passed from the base handler
@param proxy Callbacks & methods used to query for or push out data/changes