Manually created instance injection

Hi, 

I upgraded the library so that it can inject dependencies on a manually created instance. In current implementation, we have to map this instance to its class in injector, and then ask the injector for an instance of the class, which is not a very straightforward approach.

I tried to reuse as much as I could the existing API, so I just added an option to create a temporary class<->instance mapping that won't be saved in mapping builders cache.

I'm not sure to fully comply to your coding standards. I would be happy to hear your recommendations on this topic, I feel a bit lost in what I've read.

Best regards,
Fred.