Create notify method with delay, adapted tests, changed XCTFail to NSException

Hi,

* i created a notify method with a delay to also test with blocks that return immediately (see ```testBlockThatReturnImmediately```)
* removed the Network Request for the test, so now you can run the test without a internet connection
* change the XCTFail to NSException for the ```waitForStatus``` Methods, than you have the ability that catch the exception in the tests