[OE-core] opkg and gpg signed ipk packages

[Sona Sarmadi]

> > I'm guessing you would want something like this in your custom distro
> > config (or local.conf if you must):
> >
> > PACKAGECONFIG_append_pn-opkg = " sha256"
> > PACKAGECONFIG_append_pn-opkg-native = " sha256"
>

Thanks a lot guys for your help, this is now working :)
There is support for sha256 in opkg but not in the opkg-utils. 
opkg-utils (opkg.py) just uses md5 as default option. I changed 
 
opkg.py:
........
        # compute the MD5.
        if not self.fn:
            self.md5 = 'Unknown'
        else:
            f = open(self.fn, "rb")
            sum = hashlib.md5() 
to
            sum = hashlib.sha256()

and now I get checksum sha256 in the "Packages" file:

SHA256Sum: 6be1fb5b9dab3de5848fd578d515d05adc5c6cd3b0009f8c1b13ab1250cee594

Do you think this patch would be of interest for someone? 

//Sona