Removes prawcore as a requirement, lets praw manage it

requirements.txt

@@ -1,7 +1,6 @@
 arrow==0.9.0
 decorator==4.0.10
 praw==4.0.0
-prawcore==0.3.0
 PyYAML==3.12
 requests==2.12.1
 six==1.10.0

setup.py

@@ -26,7 +26,7 @@ setup(
                  "Programming Language :: Python"],
     license="FreeBSD License",
     packages=["shreddit"],
-    install_requires=["arrow", "backports-abc", "praw>=4", "prawcore", "PyYAML", "requests", "six", "tornado"],
+    install_requires=["arrow", "backports-abc", "praw>=4", "PyYAML", "requests", "six", "tornado"],
     package_data={"shreddit": ["*.example"]},
     entry_points={
         "console_scripts": [