Setup subunit-trace as an entry point

This commit moves subunit-trace into the newly created cmd dir and
adds a pbr entry point to run it as a binary. This will enable using
subunit-trace just by installing tempest-lib.

Change-Id: I3ae379edca3e776e90a18d53393c4c1424d291f7

doc/source/index.rst

@@ -23,6 +23,7 @@ Release Notes
 0.0.1
 -----
  * Adds cli testing framework
+ * Adds subunit-trace
 
 
 Indices and tables

setup.cfg

@@ -25,6 +25,10 @@ classifier =
 packages =
     tempest_lib
 
+[entry_points]
+console_scripts =
+    subunit-trace = tempest_lib.cmd.subunit_trace:main
+
 [build_sphinx]
 source-dir = doc/source
 build-dir = doc/build

tempest_lib/cmd/subunit_trace.py

@@ -236,12 +236,12 @@ def main():
         result.stopTestRun()
     if count_tests('status', '.*') == 0:
         print("The test run didn't actually run any tests")
-        return 1
+        exit(1)
     if args.post_fails:
         print_fails(sys.stdout)
     print_summary(sys.stdout)
-    return (0 if summary.wasSuccessful() else 1)
+    exit(0 if summary.wasSuccessful() else 1)
 
 
 if __name__ == '__main__':
-    sys.exit(main())
+    main()