Update .jshintrc to not warn about unused parameters.
Update .jshintrc to not warn about unused parameters.

We sometimes have unused function parameters in our code which are there to
demonstrate the function signature for use in subclasses. With the default
configuration for "unused", `jshint` likes to warn about these. This turns
those off so we only warn about unused variables, not parameters.

chipx86/reviewboard,sgallagher/reviewboard,davidt/reviewboard,sgallagher/reviewboard,brennie/reviewboard,sgallagher/reviewboard,brennie/reviewboard,davidt/reviewboard,davidt/reviewboard,chipx86/reviewboard,chipx86/reviewboard,reviewboard/reviewboard,reviewboard/reviewboard,brennie/reviewboard,sgallagher/reviewboard,reviewboard/reviewboard,reviewboard/reviewboard,davidt/reviewboard,chipx86/reviewboard,brennie/reviewboard