liboauth: bump to version 1.0.3

Add license information as well.
It could be "or GPL" as well but since we link to openssl that's a murky path
as stated in the README so just leave it at MIT.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>