Add -V/--version flag

spotdl.py

@@ -171,6 +171,11 @@ def download_single(raw_song, number=None):
 
 def main():
     const.args = handle.get_arguments()
+
+    if const.args.version:
+        print('spotdl {version}'.format(version=__version__))
+        sys.exit()
+
     internals.filter_path(const.args.folder)
     youtube_tools.set_api_key()