python-blinker: Add recipe for version 1.4

It's a fast, simple object-to-object and broadcast signaling.

Signed-off-by: Fabio Berton <fabio.berton@ossystems.com.br>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>