Added getName method to ModuleInstaller.

The getName method in ModuleInstaller becomes available after calling addModule.

This particularly heplful for setting up the module. As an example instead of using :

$this->setActionRights(1, 'Providers', 'Index');

we would use

$this->setActionRights(1, $this->getName(), 'Index');

and have less chance to have typo errors
I have followed Fork naming guidelines for it. Maybe it should stay like it is now.