e2e for ETH Classic environment

[akolotov]

The current token-bridge e2e testing assumes that networks the bridge is tested for are after the Byzantium fork at least.

But starting from omni/tokenbridge-contracts#161 we support deployment bridge contracts on the Ethereum Classic chain (as the Home side). This network has several peculiarities that are critical to handle. For example,

• no EIP658
• no EIP-211
• the same network ID for both sides of the bridge

In order to handle possible issues that could appear on the token-bridge side on earlier stages, consider to introduce a node with configuration similar to the Ethereum classic and its usage during e2e tests.