Accomodate multiple autoloaded folders

At the moment `getAppNamespace()` breaks if you have multiple source folders set in composers PSR-4 setting as it expects a string but is an array. This just first checks if its an array first then handles accordingly.
ie
This works fine
```
		"psr-4": {
			"Ntech\\": "app/"
		}
```
But this breaks
```
		"psr-4": {
			"Ntech\\": [ "app/" , "src/" ]
		}
```