dash: bump to version 0.5.8-1

Add hash file and use $(INSTALL) instead of cp for proper mode handling.

[Peter: drop /bin/sh handling as we're going to handle it globally]
Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>