Feature Request: Add support for handling exceptions

[bitcrazed]

I would like to be able to test code that throws exceptions for known states/conditions.

As per Muc's suggestion, today, my test will have to look like this:

it "should throw some exception" {
    $exceptionThrown = $false
    try {
         Cmd-ThatThrowsCoolException
    } catch [My.CoolException] {
        $exceptionThrown = $true
    }

    $exceptionThrown.should.be($true)
}

But sytnax like this is MUCH better:

Context "when the system is in a weird state" {
   It -Throws CoolException {
       ...
   }
}