Bugfix/date arg types

[cburgos]

Addresses #1662

[ghost]

Notice that other methods such as setHours also need to allow negative arguments.

[cburgos]

Noted, going through and updating the rest of the methods. Update should be ready shortly.

[alexcrichton]

Thanks! FWIW as-is this is a breaking change so we won't be able to merge this quite just yet, we're still in the process of batching breaking changes. If you'd prefer though perhaps new methods with new names could be added, and then in the next major version release we can delete all the methods and change the existing signatures?

[cburgos]

Added the other updates. @alexcrichton I think holding off and batching these with other breaking changes makes sense. Also worth noting the above commits didn't include the setFullYear and setUTCFullYear as support for optional parameters have not yet been implemented. It might make more sense to include that with #1664 for overall optional param support.

[alexcrichton]

Ok sounds good to me! I'll tag this as a breaking change and we'll merge this when we get to doing the next round of breaking changes.