Refactor watch.js
Refactor watch.js

Switched to BrowserSync's recommended post-2.0.0 syntax.

Organized logic into functions for easier reading.

Add support for customizing the BrowserSync server from 'loconfig.json'.

Example:

```json
"server": {
    "open": true,
    "https": {
        "key": "~/.config/valet/Certificates/{% paths.url %}.key",
        "cert": "~/.config/valet/Certificates/{% paths.url %}.crt"
    }
}
```

locomotivemtl/locomotive-boilerplate,locomotivemtl/locomotive-boilerplate