Added missing Unit Test for Factory

Coverage goes from:
```
Time: 1.43 seconds, Memory: 14.25Mb

OK (40 tests, 63 assertions)

Code Coverage Report:
  2014-07-21 06:45:13

 Summary:
  Classes: 60.00% (9/15)
  Methods: 78.95% (30/38)
  Lines:   84.31% (129/153)

\SlmQueue\Controller::AbstractWorkerController
  Methods: 100.00% ( 2/ 2)   Lines: 100.00% ( 14/ 14)
\SlmQueue\Controller\Plugin::QueuePlugin
  Methods:  66.67% ( 2/ 3)   Lines:  73.33% ( 11/ 15)
\SlmQueue\Factory::JobPluginManagerFactory
  Methods: 100.00% ( 1/ 1)   Lines: 100.00% (  5/  5)
\SlmQueue\Factory::QueuePluginManagerFactory
  Methods: 100.00% ( 1/ 1)   Lines: 100.00% (  5/  5)
\SlmQueue\Factory::WorkerFactory
  Methods: 100.00% ( 1/ 1)   Lines: 100.00% (  3/  3)
\SlmQueue\Factory::WorkerOptionsFactory
  Methods: 100.00% ( 1/ 1)   Lines: 100.00% (  2/  2)
\SlmQueue\Job::AbstractJob
  Methods:  50.00% ( 1/ 2)   Lines:  66.67% (  2/  3)
\SlmQueue\Job::JobPluginManager
  Methods:  50.00% ( 1/ 2)   Lines:  55.56% (  5/  9)
\SlmQueue\Options::WorkerOptions
  Methods: 100.00% ( 4/ 4)   Lines: 100.00% (  6/  6)
\SlmQueue\Queue::AbstractQueue
  Methods: 100.00% ( 5/ 5)   Lines: 100.00% ( 22/ 22)
\SlmQueue\Queue::QueueAwareTrait
  Methods: 100.00% ( 2/ 2)   Lines: 100.00% (  3/  3)
\SlmQueue\Queue::QueuePluginManager
  Methods: 100.00% ( 1/ 1)   Lines: 100.00% (  6/  6)
\SlmQueue\Worker::AbstractWorker
  Methods:  75.00% ( 6/ 8)   Lines:  85.42% ( 41/ 48)
\SlmQueue\Worker::WorkerEvent
  Methods:  50.00% ( 2/ 4)   Lines:  66.67% (  4/  6)
```

To:
```
OK (41 tests, 64 assertions)

Code Coverage Report:
  2014-07-21 06:45:04

 Summary:
  Classes: 66.67% (10/15)
  Methods: 81.58% (31/38)
  Lines:   88.00% (132/150)

\SlmQueue\Controller::AbstractWorkerController
  Methods: 100.00% ( 2/ 2)   Lines: 100.00% ( 14/ 14)
\SlmQueue\Controller\Plugin::QueuePlugin
  Methods:  66.67% ( 2/ 3)   Lines:  73.33% ( 11/ 15)
\SlmQueue\Factory::JobPluginManagerFactory
  Methods: 100.00% ( 1/ 1)   Lines: 100.00% (  5/  5)
\SlmQueue\Factory::QueueControllerPluginFactory
  Methods: 100.00% ( 1/ 1)   Lines: 100.00% (  3/  3)
\SlmQueue\Factory::QueuePluginManagerFactory
  Methods: 100.00% ( 1/ 1)   Lines: 100.00% (  5/  5)
\SlmQueue\Factory::WorkerFactory
  Methods: 100.00% ( 1/ 1)   Lines: 100.00% (  3/  3)
\SlmQueue\Factory::WorkerOptionsFactory
  Methods: 100.00% ( 1/ 1)   Lines: 100.00% (  2/  2)
\SlmQueue\Job::AbstractJob
  Methods:  50.00% ( 1/ 2)   Lines:  66.67% (  2/  3)
\SlmQueue\Job::JobPluginManager
  Methods:  50.00% ( 1/ 2)   Lines:  55.56% (  5/  9)
\SlmQueue\Options::WorkerOptions
  Methods: 100.00% ( 4/ 4)   Lines: 100.00% (  6/  6)
\SlmQueue\Queue::AbstractQueue
  Methods: 100.00% ( 5/ 5)   Lines: 100.00% ( 22/ 22)
\SlmQueue\Queue::QueueAwareTrait
  Methods: 100.00% ( 2/ 2)   Lines: 100.00% (  3/  3)
\SlmQueue\Queue::QueuePluginManager
  Methods: 100.00% ( 1/ 1)   Lines: 100.00% (  6/  6)
\SlmQueue\Worker::AbstractWorker
  Methods:  75.00% ( 6/ 8)   Lines:  85.42% ( 41/ 48)
\SlmQueue\Worker::WorkerEvent
  Methods:  50.00% ( 2/ 4)   Lines:  66.67% (  4/  6)
```