Update python version for databuilder (#229)

Author: feng-tao

README.md

@@ -12,7 +12,7 @@ Amundsen Databuilder is a data ingestion library, which is inspired by [Apache G
 For information about Amundsen and our other services, visit the [main repository](https://github.com/lyft/amundsen#amundsen) `README.md` . Please also see our instructions for a [quick start](https://github.com/lyft/amundsen/blob/master/docs/installation.md#bootstrap-a-default-version-of-amundsen-using-docker) setup  of Amundsen with dummy data, and an [overview of the architecture](https://github.com/lyft/amundsen/blob/master/docs/architecture.md#architecture).
 
 ## Requirements
-- Python = 2.7.x (And Python >= 3.x if you don't use column usage transformer as it depends on antlr python 2 runtime)
+- Python = 2.7.x or Python >= 3.6.x 
 
 ## Concept
 ETL job consists of extraction of records from the source, transform records, if necessary, and load records into the sink. Amundsen Databuilder is a ETL framework for Amundsen and there are corresponding components for ETL called Extractor, Transformer, and Loader that deals with record level operation. A component called task controls all these three components.

setup.py

@@ -55,4 +55,9 @@
         'bigquery': bigquery,
         'jsonpath': jsonpath
     },
+    classifiers=[
+        'Programming Language :: Python :: 2.7',
+        'Programming Language :: Python :: 3.6',
+        'Programming Language :: Python :: 3.7',
+    ],
 )