Switch from Big Endian to Small Endian

[terencechain]

Looks the community has favored using small endian over big endian. Let's update that in our code base: ethereum/consensus-specs#139

This applies to SSZ and another potential location is: https://github.com/prysmaticlabs/prysm/blob/master/shared/bytes/bytes.go

[nisdas]

This is only for SSZ though, unless you want to apply this across the whole repo ?

[terencechain]

Definitely for SSZ, but we should discuss whether we want to switch to small endian for the whole repo. Not sure which way I'm leaning yet

[nisdas]

I dont know if its the best to apply this across the whole repo.
Ex: Log data from the POW chain stores its integers in big-endian. It can be confusing keeping in mind all these places where it is big-endian. I am leaning towards defaulting to big-endian across our repo excluding SSZ. Afaik there is no where in our repo where we use little endian

[houjieth]

Let me fix the ssz part.