Edit the docs with new `id` generation process
Switch priority of `socket.getfqdn()` and `/etc/hostname` id guessing
Retrieve ID from cache if possible
PEP8 line length
Cache any non-IP guess of minion ID
Only log that we're guessing the ID when that is actually true
Fix out-of-date comment
Cache the minion id in /var/lib/salt or C:\salt\var\lib
Nevermind:  cache in CONFIG_DIR/minion_id
Merge pull request #7678 from basepi/idcache7558

Cache minion ID after first time guessing it, Fixes #7558