Support 0x00 as a valid hash in JSON RPC

[arnaubennassar]

Example:

for the endpoint eth_getStorageAt, this should be a valid input:

{
	"jsonrpc":"2.0", 
	"method": "eth_getStorageAt", 
	"params": [
		"0xA766B25F0577EB4802e659dF0C1bc4b3C8A0fDeD", 
		"0x00",
		"latest"
	], 
	"id": 1
}

Note that now this call would return Invalid Params, but if the 0x00 is changed to 0x0000000000000000000000000000000000000000000000000000000000000000, then the request is valid. This could affect any other endpoint that has a input param that is a hash