Adding pipeline task aliases. (#11247)

* Adding task aliases and adding `token-classification` and
`text-classification` tasks.

* Cleaning docstring.

tests/test_pipelines_text_classification.py

@@ -0,0 +1,26 @@
+# Copyright 2020 The HuggingFace Team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import unittest
+
+from .test_pipelines_common import MonoInputPipelineCommonMixin
+
+
+class TextClassificationPipelineTests(MonoInputPipelineCommonMixin, unittest.TestCase):
+    pipeline_task = "sentiment-analysis"
+    small_models = [
+        "sshleifer/tiny-distilbert-base-uncased-finetuned-sst-2-english"
+    ]  # Default model - Models tested without the @slow decorator
+    large_models = [None]  # Models tested with the @slow decorator
+    mandatory_keys = {"label", "score"}  # Keys which should be in the output