Update repository digest algorithm

[TLzyT]

When using apt > 1.2.6 SHA1 support is dropped and files are ignored. See: https://wiki.debian.org/Teams/Apt/Sha1Removal 

With apt 1.2.10 (armhf) this Warning is generated: W: http://apt.armbian.com/dists/jessie/InRelease:Signature by key DF00FAF1C577104B50BF1D0093D6889F9F0E78D5 uses weak digest algorithm (SHA1)

/etc/apt/sources.list.d/armbian.list is: deb http://apt.armbian.comjessie main