idf_tools: adds .tgz as alowed extension

tools/idf_tools.py

@@ -252,7 +252,7 @@ def mkdir_p(path):
 
 def unpack(filename, destination):
     info('Extracting {0} to {1}'.format(filename, destination))
-    if filename.endswith('tar.gz'):
+    if filename.endswith(('.tar.gz', '.tgz')):
         archive_obj = tarfile.open(filename, 'r:gz')
     elif filename.endswith('zip'):
         archive_obj = zipfile.ZipFile(filename)