Demote datastore edits to info status

SeeRM #8498
Add an environment option to suppress info msgs

It's often you want counts of just WARN and ERROR messages, and don't
want to spam yourself with INFO messages that you don't intend to
address anyway. This is most often the case with CI, such as with

https://travis-ci.org/todb-r7/metasploit-framework
Fix the last of the Set-Cookie msftidy warnings
Land #3400, last msftody set-cookie warnings
Land #3380, datastore msftidy errors set to INFO

[SeeRM #8498]