Use only one poller in salt-minion + add logging

Using only one poller in salt-minion means that the salt-minion
interleaves handling of execution requests and events.
Fix pylint errors and delete commented code
Fix usage of logging pylint errors
Fix unicode decode error in logging
Add gather_job_info config option
Fix lazy merge
Merge pull request #10063 from mbirtwell/fix_a_missing_returns_case_develop

Fix a case when job returns are missed by salt because saltutil.find_job times out