> Jackson2 and its compatibility with Jackson1

There is no any compatibility: they live in different packages, but they both provide similar JSON. I think we can create JSON from J1 and deserialize it in J2 and, of course, vise versa.
>we might need the option to force the use of Jackson1 if both are available.

I don't think so. It can be achieved via simple config manipulation. Take a look into tests within this PR.
Eventually J1  will sink into oblivion and we will have to remove **force** attribute.

So, 
1. Will I rename our abstraction to the `JsonMapper` or `ObjectMapper`?
2. Will it be OK that I say J1 reference is deprecated?
3. Should we allow to provide reference to the J2? There will be a lot of parser logic and eventually someone would say that he wants to have a reference to gson not SI-strategy.
4. Is it OK to go ahead and polish `Json*MessageMapper`? BTW should they support both Jacksons too?
5. WDYT about `ObjectToMapTransformer` ?