pull setup.py install_requires from requirements.txt

Instead of hard-coding it in both places.  When I changed the redis
requirement in requirements.txt I missed it in setup.py

Author: joeshaw

setup.py

@@ -20,10 +20,9 @@
     pyres_worker=pyres.scripts:pyres_worker
     """,
     install_requires=[
-        'simplejson>=2.0.9',
-        'redis==2.4.12',
-        'setproctitle>=1.0'
-    ],
+            item for item in
+            open("requirements.txt").read().split("\n")
+            if item],
     classifiers = [
             'Development Status :: 4 - Beta',
             'Environment :: Console',