Adding toNever expectation

[rkreutz]

Adding a new expectation toNever, which will check a predicate so a value never matches that predicate. As opposed to toEventuallyNot, this expectation will fail if at some given point during the timeout interval the value matches the predicate.

• Does this have tests? Added positive and negative matches to the new expectation
• Does this have documentation?
• Does this break the public API (Requires major version bump)?
• Is this a new feature (Requires minor version bump)? Yes

[ikesyo]

Thanks for the contribution 👏