Expose SAMOptions to I2PListener

[a-0-dev]

I would like to have access to manually setting the SAMOptions for my I2PListener. Before I go ahead and code something for a PR, would the following approach be okay for you?

Since there are already different functions for creating an I2PListener, I would implement an I2PListenerBuilder where one can first set all options as one likes and then calling a build() function on that builder returns the I2PListener just as the different bind functions do it now.

If you have any other suggestion, I'm happy to hear about it and will try to integrate it. I'm planning on using this lib for a personal project of mine, I'm happy to contribute something as well :)

[eyedeekay]

Please feel free to implement your proposal and make a PR at any time.

[a-0-dev]

Implemented in #20