use requirements.txt in setup.py

Author: charliestrawn

MANIFEST.in

@@ -0,0 +1 @@
+include requirements.txt

readme.md

@@ -9,7 +9,7 @@ A Python async client for the [NATS messaging system](https://nats.io).
 ## Supported platforms
 
 Should be compatible with following versions of [Python](https://www.python.org/)
-using [Tornado 4.2+](https://github.com/tornadoweb/tornado/tree/v4.2.0)
+using [Tornado 4.2+](https://github.com/tornadoweb/tornado/tree/v4.2.0) (less than 5.0)
 with [gnatsd](https://github.com/nats-io/gnatsd) as the server:
 
 - 2.7.x

setup.py

@@ -1,6 +1,11 @@
+import os
 from setuptools import setup, find_packages
 from nats import __version__
 
+this_dir = os.path.dirname(os.path.abspath(__file__))
+with open(os.path.join(this_dir, 'requirements.txt')) as f:
+    requirements = f.read().splitlines()
+
 setup(
     name='nats-client',
     version=__version__,
@@ -11,7 +16,7 @@
     author_email='[email protected]',
     license='Apache 2.0 License',
     packages=['nats', 'nats.io', 'nats.protocol'],
-    install_requires=['tornado>=4.2'],
+    install_requires=requirements,
     zip_safe=True,
     classifiers=[
         'Intended Audience :: Developers',