deque: time to finish lab1
deque-view: initial commit
deque-vm: initial commit
deque-vm: add status and observer for StringProperty
deque-vm: check input format
deque-vm: disable add buttons if input is incorrect
deque-vm: disable getting from deque when it is empty
deque-vm: add getters

refactor ViewModel and Deque
deque: connect view and viewmodel
deque: rename txt field
deque: make gradle happy
deque: try to make Travis happier
deque: correct remove tests

Refactor getters in VM.
deque: replace method reference by pattern Command

I'm really disapointed about this change.
deque: modify enum name
Merge pull request #118 from VVillwin/lab2-mvvm-javafx

Вильчинский - Лабораторная работа #2