validate the backup format

src/apps.js

@@ -458,14 +458,6 @@ function validateCsp(csp) {
     return null;
 }
 
-function validateBackupFormat(format) {
-    assert.strictEqual(typeof format, 'string');
-
-    if (format === 'tgz' || format == 'rsync') return null;
-
-    return new BoxError(BoxError.BAD_FIELD, 'Invalid backup format');
-}
-
 function validateUpstreamUri(upstreamUri) {
     assert.strictEqual(typeof upstreamUri, 'string');
 
@@ -2205,7 +2197,7 @@ async function importApp(app, data, auditSource) {
     let restoreConfig;
 
     if (data.remotePath) { // if not provided, we import in-place
-        error = validateBackupFormat(backupFormat);
+        error = backups.validateBackupFormat(backupFormat);
         if (error) throw error;
 
         // TODO: make this smarter to do a read-only test and check if the file exists in the storage backend