when contract migrated, write address into web subproject

[gasolin]

currently, we have to manually write CONTRACT_ADDRESS when contract migrated.

in contract migration script we could get contract deployed address.

We could write these addresses into web subproject autimatically, ex in /lib/addresses.js with format

export const CONTRACTNAME1_ADDRESS = '0x....';
export const CONTRACTNAME2_ADDRESS = '0x....';

[gasolin]

soft link might works https://truffleframework.com/tutorials/getting-started-with-drizzle-and-react#link-up-our-build-artifacts