Fix stub id prefix

[mantoni]

Purpose (TL;DR) - mandatory

Each spy, stub and fake exposes an id property which should be named spy#{n}, stub#{n} and fake#{n} with {n} being incremented for each new instance. In case of a stub this property is generated but then replaced with spy#{n} due to a wrong function call order. This pull request fixes this and adds missing test cases (there was one for fakes, but none for spy or stub).

How to verify - mandatory

1. Check out this branch
2. npm install
3. npm test

Checklist for author

• npm run lint passes
• References to standard library functions are cached.

[mroderick]

This has been published as sinon@5.0.7

[mantoni]

Thank you 🙂