Msftidy should merely INFO on datastore edits

See the redmine bug [note 16](https://dev.metasploit.com/redmine/issues/8498#note-16) for reasoning. I think it's sound. If I'm crazy (looking at you @limhoff-r7 and @jlee-r7) then please stop me and we'll go through and fix these datastore edits for real. I just don't any case where someone has complained of a module failing, under any circumstance, when the datastore is edited at runtime.

@jvazquez-r7 has a theory that some edits can mess up payload generation, but I expect those cases are only when rport/rhost/lport/lhost is modified at runtime. If that's true, we should tighten up the WARN rule just for that.

## Verification

 - [ ] Run `tools/msftidy modules | grep ERROR | wc -l` and see a large number (around 132, which is the current count).
- [ ] Switch to this branch, or merge this branch, and run the same command, seeing a small number of errors (I count 2 right now)
- [ ] Run `tools/msftidy modules |grep INFO | wc -l' and see a large number (156 right now).
- [ ] Run `MSF_SUPPRESS_INFO_MESSAGES=1 tools/msftidy.rb modules/
|grep INFO | wc -l' and see a large a smaller number (under 50).
- [ ] Merge with a merge message in the body of `SeeRM 8498` in order to update the Redmine ticket.

Note that developers should not avoid the INFO message via environment vars, this change is pretty just to keep travis log lines a little reasonable.