Auth fluent interface and exception handling

[whera]

It was added two new classes:

• [MikrotikAPI\Util\Validation] that has methods to validate the fields;
• [MikrotikAPI\MikrotikException] responsible for the regenciar exeções the componet.

In Auth class was added validations of fields, exeções, transofrmado in fluent interface and adicionandador PSR-2 rules.

I hope that the changes can be helped.