Custom media types aren't handled properly when originating in setUri()

[avoidwork]

The setUri() method calls sync() which has no ability to do a custom transformation of the data it receives from request() creating a potential gap in functionality for developers dealing with unofficial media types.

A custom tranform that fires when the arg is a text should be good enough to intercept & handle the text string.

Most likely it's reasonable to create an onrequest() function which accepts the input at https://github.com/avoidwork/haro/blob/master/src/haro.js#L501 if the typeof is "string".