Utilize timeout in net_response plugin.

Also changing the net_response and http_response plugins to only accept
duration strings for their timeout parameters. This is a breaking config
file change.

closes #1214

etc/telegraf.conf

@@ -680,7 +680,7 @@
 #   ## Server address (default http://localhost)
 #   address = "http://github.com"
 #   ## Set response_timeout (default 5 seconds)
-#   response_timeout = 5
+#   response_timeout = "5s"
 #   ## HTTP Request Method
 #   method = "GET"
 #   ## Whether to follow redirects from the server (defaults to false)
@@ -946,14 +946,15 @@
 #   protocol = "tcp"
 #   ## Server address (default localhost)
 #   address = "github.com:80"
-#   ## Set timeout (default 1.0 seconds)
-#   timeout = 1.0
-#   ## Set read timeout (default 1.0 seconds)
-#   read_timeout = 1.0
+#   ## Set timeout
+#   timeout = "1s"
+# 
 #   ## Optional string sent to the server
 #   # send = "ssh"
 #   ## Optional expected string in answer
 #   # expect = "ssh"
+#   ## Set read timeout (only used if expecting a response)
+#   read_timeout = "1s"
 
 
 # # Read TCP metrics such as established, time wait and sockets counts.
@@ -1144,6 +1145,9 @@
 #   ## user as argument for pgrep (ie, pgrep -u <user>)
 #   # user = "nginx"
 # 
+#   ## override for process_name
+#   ## This is optional; default is sourced from /proc/<pid>/status
+#   # process_name = "bar"
 #   ## Field name prefix
 #   prefix = ""
 #   ## comment this out if you want raw cpu_time stats