Make Buildbot masters send ts_mon metrics, and add standard HTTP server metrics.

scripts/common/env.py

Index: scripts/common/env.py
diff --git a/scripts/common/env.py b/scripts/common/env.py
index 76d93a0ca8d885b5d046e21ed7412016deed3a68..eb66cfd24b3ba0058967b6578e5f247a36878731 100755
--- a/scripts/common/env.py
+++ b/scripts/common/env.py
@@ -65,6 +65,7 @@ def path_if(*args):
 Build = path_if(os.path.dirname(__file__), os.pardir, os.pardir)
 # The path to the <build_internal> directory.
 BuildInternal = path_if(Build, os.pardir, 'build_internal')
+Infra = path_if(Build, os.pardir, 'infra')
 
 
 def SetPythonPathEnv(value):
@@ -371,6 +372,7 @@ def GetInfraPythonPath(hermetic=True, master_dir=None):
   if master_dir:
     path += GetMasterPythonPath(master_dir)
   path += GetBuildPythonPath()
+  path += Infra
   path += GetSysPythonPath(hermetic=hermetic)
   return path