added tasks and tests for class Animal
added animal class
added new tasks
database file
zoo class almost ready, .gitignore changed too
delete __pycache__ directory
add insert_animal method
add insert_method
add remove_animal method
added get_last_breed method
changed db_name argument to default on DataBase-class
tasks managed and some changes to database and zoo added too
get_gestation method added
will it mate method added
Merge pull request #2 from LachezarStoev/mating-methods

merged master with mating-methods