Interactive demos

[Grawl]

• Added interactive elements using stores
• Every console.log is described to know why it appears in browser console
• Updated required Node version to match @quasar/app requirements
• Do not open browser when dev server is started (it's very annoying when I restart quasar dev on each quasar.conf.js change)
• Added dev and build scripts to run yarn dev or yarn build
• Added "module" store to demonstrate access from one store to another

[TobyMosque]

since your improvements are overlaping with the changes what i did, I'll probably reject that PR

[Grawl]

I can rebase, just want to make this repository a better demo with more clear usage examples

[Grawl]

ok i just merged it