Add the start message for debugging net info

When a network scenario test fails due to networking timeout, we can
get both server console log and network information for debugging.
Current network information doesn't contain the start message and
it seems a little confusion where starts network info.
This patch adds the message.

Change-Id: I8490c08b7073302d299f7b63dd9d6380d8a8d27e
Related-Bug: #1323658
Merge "Add the start message for debugging net info"