Added CUploadedFile::getBaseName() method: returns file name without extension

Use case of this tiny neat helper method. Some hypothetical code before:
```php
/* @var $logotype CUploadedFile */
$baseName=substr($logotype->name,0,strlen($logotype->name)-strlen($logotype->extensionName)-1);
$this->logotypeName=SomeHelper::random().'-'.SomeHelper::slugify($baseName).'.'.$logotype->extensionName;
```

And after this enhancement:
```php
/* @var $logotype CUploadedFile */
$this->logotypeName=SomeHelper::random().'-'.SomeHelper::slugify($logotype->baseName).'.'.$logotype->extensionName;
```