TokenNetworkRegistry should check chain_id before calling createERC20TokenNetwork()

[pirapira]

TokenNetworkRegistry class's add_token() calls createERC20TokenNetwork() function of the TokenNetworkRegistry smart contract. This call fails when chain_id stored in the smart contract is zero.

This issue keeps track of adding

• a precondition check against zero chain_id
• a post-failure check against zero chain_id

[pirapira]

This is a part of #4792.

[rakanalh]

Replied in other issues, but any constructor-(require|assert) in the contract doesn't need to be checked in the proxy methods.