RecycleView does not update after swipe to delete inside ShowFlashCardsActivity

[eXeeLD]

Must be resolved before #26

How to reproduce

1. Add 3 question and answers
2. Delete the second item

Issue example

https://i.imgur.com/rJCZaio.png

[eXeeLD]

@srv-twry done #8, #23, #26, #27 review the pull request please