Fix short address decoding (develop branch)

[k06a]

Example addresses:

0x0014F55A50b281EFD12294f0Cda821Bd8171e920
0x0000000000000000000000000000000000000000

[yaronvel]

Hi, thanks for changing the branch.
But still, can you explain why this change is needed?
why should we support addresses longer than 20 bytes?

[k06a]

@yaronvel no, you should support addresses shorter than 20 bytes, because it could contain first zero bytes for the probability reasons.

Encoders could encode addresses as numbers and use for example 19 or 18 bytes for some addresses, this is an absolutely valid case for abstract RLP encoder.