Configurable spec/suite filename detection

* Adds extraItStackFrames and extraDescribeStackFrames config properties.
* Un-deprecates the filename properties of reporter events.
* Fixes #2065.

spec/helpers/callerFilenameShim.js

@@ -0,0 +1,5 @@
+(function() {
+  specHelpers.callerFilenameShim = function(fn) {
+    return fn();
+  };
+})();