Runtime: Add fake runtime 'test' - for testing purposes.
XHR: Default to application/octet-stream for unknown mime types. Address #36.
XHR, Flash: When sending single blob, set it's content-type in the shim, rather than from outside.
XHR, Flash/Silverlight: Add support for sending detached blobs.
Tests, XHR: When sending blob, actually do send the blob.