Add insert, insertWithTransaction and InsertOrFail methods

[artem-prozorov]

1. In repository contract ( https://github.com/artem-prozorov/repos/blob/master/src/Contracts/RepositoryInterface.php ) add 3 methods:

• insert(array $data): bool - this method inserts data into the data storage
• insertWithTransaction(array $data): bool - opens transaction, inserts data and closes transaction. Rolls the transaction back if the data cannot be inserted (partially or completely)
• insertOrFail(array $data): void - does exactly the same as insertWithTransaction but throws exception if the data cannot be inserted

2. Change Abstract repository, Array Repository and Fixturable repository accordingly (https://github.com/artem-prozorov/repos/blob/master/src/AbstractRepository.php, https://github.com/artem-prozorov/repos/blob/master/src/ArrayRepository.php and https://github.com/artem-prozorov/repos/blob/master/src/FixturableRepository.php)

[artem-prozorov]

Done, will appear in the second release