Encrypt passwords in DB (#1187)

* Encode/Encrypt passwords in DB

* Only decrypts passwords if it is necessary

* Add tests for encryption functions

tests/mock_user_repo.go

@@ -49,6 +49,10 @@ func (u *MockedUserRepo) FindByUsername(username string) (*model.User, error) {
 	return usr, nil
 }
 
+func (u *MockedUserRepo) FindByUsernameWithPassword(username string) (*model.User, error) {
+	return u.FindByUsername(username)
+}
+
 func (u *MockedUserRepo) UpdateLastLoginAt(id string) error {
 	return u.Err
 }