Add detailed troubleshoot guide for client testing

[xinaxu]

Add detailed troubleshoot guide for client testing to list down all caveats, where and what to look for in logs, etc. This can be put into troubleshoot.md and linked in readme.md

This should at least cover

1. where to find out whether the deals have been sent out and corresponding success/error message
2. why no deals are sent out (is it below 16GB threshold)
3. what logs of deal tracker means