Web3 v1.0

[adrianmcli]

This PR seeks to overhaul the Truffle box in many ways, read on to find out more.

Done

The following items have already been implemented in this PR.

Frontend client

• Replaced old React frontend with a new one located in its own separate folder /client.
  • Uses non-ejected Create-React-App as its base.
• Uses Web3 v1.0-beta.35 (note: currently, only for the React app).
• Uses custom script in getContractInstance.js to replace truffle-contract dependency (this can change).
• Uses a link-contracts npm script to create a symlink in the src folder
  • This links to the json contract build artifacts folder in the outer Truffle project

Truffle project

• Update truffle-box.json to use new scripts when unboxing.
• Update test code to use Async/Await Javascript pattern.
• Bump Solidity pragma versions to ^0.4.24.

How to test (i.e. try it out)

1. Checkout the branch:

   git checkout web3-v1.0

2. Run truffle develop and then run tests, compile, and migrate:

   truffle develop
   truffle(develop)> test
   truffle(develop)> compile
   truffle(develop)> migrate --reset

3. In a new terminal, navigate to the client folder, install dependencies, and run the link contracts script:

   cd client
   npm install
   npm run link-contracts

4. Start the frontend client with npm start.

5. Make sure you are using a browser where MetaMask is disabled (we will add support for this later, see above) and navigate to http://locahost:3000 in your browser.

6. Observe that the stored value is 5.

[adrianmcli]

@DiscRiskandBisque I've added a windows script for linking contracts: https://github.com/truffle-box/react-box/pull/65/files#diff-52dbbf94d5c54b68c0cad0702ba94a96R19

"script": {
  "link-contracts": "run-script-os",
  "link-contracts:linux:darwin": "cd src && ln -s ../../build/contracts contracts",
  "link-contracts:win32": "cd src && mklink \\D C:\\..\\build\\contracts contracts"
}

The run-script-os devDependency will run the right script depending on the machine's OS.

This PR is now ready to be merged.

[adrianmcli]

@DiscRiskandBisque

I'm using the following script for making a symlink on Windows, I grabbed it from your edit to my tutorial:

mklink \D C:\..\build\contracts contracts

But shouldn't it be a relative symlink instead? Something like:

mklink \D ..\..\build\contracts contracts

For reference, the linux version is:

ln -s ../../build/contracts contracts