Make scripts and entry_points mutually exclusive based on setuptools …

…presence (#650)

When installing newrelic-admin with setuptools, the newrelic-admin shim is written to bin multiple times due to the inclusion of both `scripts` and `entry-points` as arguments to `setup`. This poses problems for installers that comply with newer PEP standards, such as the Pypa `installer` package: https://github.com/pypa/installer

setup.py

@@ -154,14 +154,15 @@ def build_extension(self, ext):
     package_data={
         "newrelic": ["newrelic.ini", "version.txt", "packages/urllib3/LICENSE.txt", "common/cacert.pem"],
     },
-    scripts=["scripts/newrelic-admin"],
     extras_require={"infinite-tracing": ["grpcio", "protobuf"]},
 )
 
 if with_setuptools:
     kwargs["entry_points"] = {
         "console_scripts": ["newrelic-admin = newrelic.admin:main"],
     }
+else:
+    kwargs["scripts"] = ["scripts/newrelic-admin"]
 
 
 def with_librt():