*8358* Disable genre selector for reviewer file attachment uploads

Bugzilla ticket: http://pkp.sfu.ca/bugzilla/show_bug.cgi?id=8358

I had to analyze all the classes involved in file uploading to make sure I don't break anything. I will attach my notes here for safekeeping:

```
_SubmissionFileDAODelegate_

ArtworkFileDAODelegate extends SubmissionArtworkFileDAODelegate (final) - no genre

SubmissionArtworkFileDAODelegate extends SubmissionFileDAODelegate - no genre
ArticleFileDAODelegate extends SubmissionFileDAODelegate (final) - no genre

SubmissionFileDAODelegate extends DAO

    * 3 references to genre (get/setters)
        No rewrite required null handling is already implemented

DAO - no genre


_PKPFileDAO_

SubmissionFileDAO extends PKPSubmissionFileDAO (final)

    * function getGenreCategoryMapping()
        overwrites PKPSubmissionFileDAO::getGenreCategoryMapping
        no rewrite required fall back to GENRE_CATEGORY_DOCUMENT

PKPSubmissionFileDAO extends PKPFileDAO

    * function &insertObject(&$submissionFile, $sourceFile, $isUpload = false) {
        utilizes: _castToGenre and _getFileImplementationForGenreId
        no changes required (resolved by changing _getFileImplementationForGenreId)

    * function &updateObject(&$updatedFile, $previousFileId = null, $previousRevision = null) {
        utilizes: _castToGenre and _getFileImplementationForGenreId
        calls: setGenreId getGenreId
        no changes required (resolved by changing _getFileImplementationForGenreId)

    * function &setAsLatestRevision($revisedFileId, $newFileId, $submissionId, $fileStage) {
        used in ./lib/pkp/controllers/wizard/fileUpload/form/SubmissionFilesUploadConfirmationForm.inc.php
        no rewrite required

    * function newDataObjectByGenreId($genreId)
        used in ./lib/pkp/classes/file/SubmissionFileManager.inc.php
        no changes required (resolved by changing _getFileImplementationForGenreId)

    * function getGenreCategoryMapping() {
        placeholder to ensure that child class implements method
        no rewrite required

    * function &_getFileImplementationForGenreId($genreId) {
        no external references
        IMPLEMENTED fall back to GENRE_CATEGORY_DOCUMENT

    * function &_getDaoDelegateForGenreId($genreId) {
        no external references
        no changes required (resolved by changing _getFileImplementationForGenreId)

    * function &_castToGenre($submissionFile) {
        no external references
        no changes required (resolved by changing _getFileImplementationForGenreId)



ArticleFileDAO extends PKPFileDAO (final) - no genre
IssueFileDAO extends PKPFileDAO (final) - no genre

PKPFileDAO extends DAO - no genre
DAO - no genre


_PKPFile_

ArtworkFile extends ArticleFile - no genre
ArticleFile extends SubmissionFile

    * function _generateFileName()
        No rewrite required works with genreId null too

SubmissionFile extends PKPFile

    * function setGenreId($genreId)
        No rewrite required null values are already implemented
    * function getGenreId()
        No rewrite required null values are already implemented
    * function _generateFileName()
        genrates file name based on genre
        No rewrite required works with genreId null too

PKPFile extends DataObject - no genre
DataObject - no genre
```