Make skipInterceptor take a anon fn as param to make interception customisable

[zakhenry]

Ie change interface

skipInterceptor():NgRestAdapter.NgRestAdapterService;

to

skipInterceptor(shouldSkip?:ISkipInterceptorFunction):NgRestAdapter.NgRestAdapterService;

Where ISkipInterceptorFunction is

interface ISkipInterceptorFunction {
    (rejection:ng.IHttpPromiseCallbackArg<any>):boolean;
}