updated joyride typings to have optional setting parameters

http://www.typescriptlang.org/Handbook#writing-dts-files

> Callbacks
Many JavaScript libraries take a function as a parameter, then invoke that function later with a known set of arguments. When writing the function signatures for these types, do not mark those parameters as optional. The right way to think of this is "What parameters will be provided?", not "What parameters will be consumed?". While TypeScript 0.9.7 and above does not enforce that the optionality, bivariance on argument optionality might be enforced by an external linter.

Is this change is valid?