Add addPresenters() to PresenterManager
Add addPresenters() to PresenterManager

Fixes #98
bobthecow/psysh,adetch/psysh,mubassirhayat/psysh,damiankloip/psysh,damiankloip/psysh,mubassirhayat/psysh,barryvdh/psysh,damiankloip/psysh,bobthecow/psysh,lvht/psysh,lvht/psysh,barryvdh/psysh,adetch/psysh