Added `dismissNotification` to immediately dismiss the current notification

Fixes #26
Relates to #6
Will probably conflict massively with #1 (How did I miss that thread!)

The first two commits were done to allow access to the views and animations in other methods, they were trapped in the scope of `displayNotification:`.

I think you've been working on something similar @cruffenach, will be interesting to see how you tackled it, I hope this PR is of use to you in some way.

:cold_sweat: