Add placeholder CRLCrashManualNotify

Hey! I've been using CrashProbe to test the new Bugsnag notifier (We actually started work on this before we got listed on crashprobe.com, but our bad score there was one of the main reason's we're improving it).

One of the features I needed to test that wasn't exposed was sending a manual notification. Would be great to have this ability in the app, even if it's not used in the comparison charts.