Update documentation for angularjs $httpBackend expect methods.

Both `expect`, `expectPOST`, `expectPUT` and `expectPATCH` accept the following types for `data`:
- string
- RegExp
- function(string)
- Object

This can be seen in https://github.com/angular/angular.js/blob/master/src/ngMock/angular-mocks.js#L1500-L1506

Definition will be simpler if we just allow `data` to have type `any`.