Sort the tokens table by contract address

... to make our builds reproducible again.

Fixes keepkey/keepkey-firmware#212

keepkeylib/eth/ethereum_tokens.py

@@ -44,7 +44,7 @@ def build(self):
                 self.add_tokens(network)
 
     def serialize_c(self, outf):
-        for token in self.tokens:
+        for token in sorted(self.tokens, key=lambda t: t.token['address']):
             token.serialize_c(outf)
 
 def is_ascii(s):