PropertyChangedEventArgs invoker method

I had a type that inherited from ObservableCollection, and the [OnPropertyChanged](http://msdn.microsoft.com/en-us/library/ms654935.aspx) method took a PropertyChangedEventArg instead of a string. Therefore Fody could not find it.

Also the warning for this problem was long, and buried the name of the offending type too far into the message.

>Could not derive or inject 'OnPropertyChanged, NotifyOfPropertyChange, RaisePropertyChanged, NotifyPropertyChanged, NotifyChanged, raisePropertyChanged' into 'BranchCollection'. It is possible you are inheriting from a base class and have not correctly set 'EventInvokerNames' or you are using a explicit PropertyChanged event and the event field is not visible to this instance. Please either correct 'EventInvokerNames' or implement your own EventInvoker on this class. No derived types will be processed. If you want to suppress this message place a [DoNotNotifyAttribute] on BranchCollection.

I changed the error message to

>Could not find EventInvoker method on type 'BranchCollection'. Possible names are 'OnPropertyChanged, NotifyOfPropertyChange, RaisePropertyChanged, NotifyPropertyChanged, NotifyChanged, raisePropertyChanged'. It is possible you are inheriting from a base class and have not correctly set 'EventInvokerNames' or you are using a explicit PropertyChanged event and the event field is not visible to this instance. Please either correct 'EventInvokerNames' or implement your own EventInvoker on this class. No derived types will be processed. If you want to suppress this message place a [DoNotNotifyAttribute] on BranchCollection.