Add waitForRequest Method

[diegogit03]

Add this method to track and await requests from javascript and return fake responses.
I want improve the tests, but i dont know how test the js funcionality. Maybe write a non-unit test?

[taylorotwell]

Thanks for your pull request to Laravel!

Unfortunately, I'm going to delay merging this code for now. To preserve our ability to adequately maintain the framework, we need to be very careful regarding the amount of code we include.

If applicable, please consider releasing your code as a package so that the community can still take advantage of your contributions!

[diegogit03]

Thank you Taylor i will do it