Fix two common needs

[zouyuefu]

Hi all,
there are two needs during the using of EventBus.

1. Because of the complex lifecycle of activities, fragments, and so on, we offten need to register the same object again. But it's not allowed in EventBus.
2. We have some tool class, only provide some static method, currently it's not support in EventBus.

I add these two functions, pls help have a review.

[william-ferguson-au]

1. You should be registering with eventBus at the start of your Activity/Fragments lifecycle and unsubscribing at the end of the lifecycle. Eg onCreate/onDestroy, onStart/onStop. Whatever makes most sense.

2. Yet another good reason not to use static tool classes. Work out what your tool your tool class actually represents. Name it properly and create an instance of it. If you really only have a single instance of it and you absolutely have to make it available to every man and his dog and can't inject it, then make a static member to hold the instance. Once you start treating everything like an object you'll be surprised at the freedom you get.