OS X cli updater output confusing

Thought I'd check for an update:

```
$ keybase update check
This is no longer supported. Instead you can run:

/Applications/Keybase.app/Contents/SharedSupport/bin/updater check
```

I have that in my $PATH, so:

```
$ updater check
2016/09/05 09:01:02 DEBG Using default path to keybase: /Applications/Keybase.app/Contents/SharedSupport/bin/keybase
2016/09/05 09:01:02 DEBG Execute: /Applications/Keybase.app/Contents/SharedSupport/bin/keybase [version -S]
2016/09/05 09:01:02 DEBG Execute: /usr/bin/sw_vers [-productVersion]
2016/09/05 09:01:02 INFO Checking for update, current version is 1.0.17-20160829110024+c4e8dc8
2016/09/05 09:01:02 INFO Using updater source: Keybase.io
2016/09/05 09:01:02 DEBG Using options: updater.UpdateOptions{Version:"1.0.17-20160829110024+c4e8dc8", Platform:"darwin", DestinationPath:"/Applications/Keybase.app", URL:"", Channel:"", Env:"prod", Arch:"amd64", Force:false, OSVersion:"10.11.6", UpdaterVersion:"0.2.5"}
2016/09/05 09:01:02 INFO Request "https://api.keybase.io/_/api/1.0/pkg/update.json?auto_update=0&install_id=22b5b34ecc20145062d8b3dc1d0568a189315df376f4801d&os_version=10.11.6&platform=darwin&run_mode=prod&upd_version=0.2.5&version=1.0.17-20160829110024%2Bc4e8dc8"
2016/09/05 09:01:03 DEBG Received update response: updater.Update{Version:"1.0.17-20160829110024+c4e8dc8", Name:"v1.0.17-20160829110024+c4e8dc8", Description:"Recent changes:\n---------------\n- Search from the app! Want to share data in KBFS with a Twitter user? Just click the Twitter bird and type their username. This will popup a folder for you, and if they're not on Keybase yet, and invitation code to share.\n\n- Support for macOS 10.12 (Sierra)\n\n- Introducing the main GUI screen. This is where you'll look people up, manage your folders, and perform other actions. A lot of the features are stubbed out, but you can start playing with it.\n\n- Sharing before signup! Go ahead and put data in /keybase/private/you,friend@twitter/. If you have any invite codes, this will pop up a window with a link to DM them. It also works for end-to-end encryption with Reddit, Coinbase, Github, and Hacker News users.\n\nSmall stuff:\n--------------\n- Various bug fixes and improvements\n\nWhat we are currently working on:\n---------------------------------\n- KBFS performance, including delayed writes\n- profile editing and proof generation inside the GUI\n", InstallID:"22b5b34ecc20145062d8b3dc1d0568a189315df376f4801d", RequestID:"", Type:0, PublishedAt:1472468424000, Asset:(*updater.Asset)(0xc420124be0), NeedUpdate:false}
```

Shouldn't these log entries be going somewhere else? And then a simple "You are already up to date." or something like that?

I should note that I installed Keybase.app in my own ~/Applications, which I know isn't supported (I have adjusted the paths in the above output).

Reproduce the two entry points shown: `keybase update check` and `updater check`, using the macOS installation paths in the report. Trace where the updater emits its log output and handles `NeedUpdate:false`; done means the check presents a concise up-to-date message without confusing debug output.

Written by the indexing model from the issue text.