test xml, model classes and xml parsing for test were added
all structure of classes and work with sql for test was added
Merge branch 'master' of https://github.com/margaritazainullina/LanguageTrainer

Conflicts:
	assets/level_def_test.xml
	src/ua/hneu/languagetrainer/App.java
	src/ua/hneu/languagetrainer/model/tests/Answer.java
	src/ua/hneu/languagetrainer/model/tests/Question.java
	src/ua/hneu/languagetrainer/model/tests/Test.java