Automatically download converted models from the Hugging Face Hub (#70)

* Automatically download converted models from the Hugging Face Hub

* Remove unused import

* Remove non needed requirements in dev mode

* Remove extra index URL when pip install in CI

* Allow downloading to a specific directory

* Update docstring

* Add argument to disable the progess bars

* Fix typo in docstring

tests/test_utils.py

@@ -0,0 +1,17 @@
+import os
+
+from faster_whisper import download_model
+
+
+def test_download_model(tmpdir):
+    output_dir = str(tmpdir.join("model"))
+
+    model_dir = download_model("tiny", output_dir=output_dir)
+
+    assert model_dir == output_dir
+    assert os.path.isdir(model_dir)
+    assert not os.path.islink(model_dir)
+
+    for filename in os.listdir(model_dir):
+        path = os.path.join(model_dir, filename)
+        assert not os.path.islink(path)