Feature request: "keybase log view" to show logs

I know `keybase log send` is a well known way to have the logs sent to the Keybase team. However, it took me a minute to figure out where I can see the logs as a user.

The first place I checked was `keybase help log`, only to find out that `send` is the only available subcommand.

Then I checked `/var/log` and was disappointed to find no keybase logs there.

What happened then was @reub's [attached console output](https://github.com/keybase/client/issues/8894#issuecomment-335224638) in #8894 tipped me off that keybase has plist files in `~/Library/LaunchAgents` and those files happen to contain explicit references to their respective logs situated in `~/Library/Logs`.

So now I'm enjoying the magnificently detailed chronicles of the operation of the keybase components which currently have the privilege of taking part in the runtime of my system:

```
$ ls -l ~/Library/Logs/keybase*
-rw------- 1 specious staff 51646090 Dec 22 17:38 /Users/specious/Library/Logs/keybase.kbfs.log
-rw------- 1 specious staff 7578670 Dec 22 17:25 /Users/specious/Library/Logs/keybase.service.log
-rw------- 1 specious staff 134217923 Dec 22 12:55 /Users/specious/Library/Logs/keybase.service.log-20171222T125345-0500-20171222T125547-0500
-rw-r--r-- 1 specious staff 0 Nov 3 17:29 /Users/specious/Library/Logs/keybase.start.log
-rw-r--r-- 1 specious staff 885211 Dec 22 16:53 /Users/specious/Library/Logs/keybase.updater.log
```

Still curious if the desktop GUI and the CLI utility keep their own logs in a different location, or if the service daemon is responsible for logging everything on their behalf...

Now, I'm not saying I'm the smartest keybase user or that I'm certain that information about where to look isn't posted somewhere obvious that I didn't check. However, my understanding is that Keybase's mission is to assure users of the software's transparency, so I'd like to float the idea of including a subcommand in the `keybase log` function such as `show` or `view` that will allow users to easily retrieve the logs without having to figure out where they are stored on their system.

This will also provide a useful abstraction over the difference regarding the location of the logs on the various platforms such as macOS, Linux, Windows and (I'm hoping) mobile devices that have legitimately useful command line support in the future.

Start by locating the CLI implementation of `keybase log` and its existing `send` subcommand. Trace how log locations differ across macOS, Linux, Windows, and mobile, then identify the project’s existing tests or platform-specific entry points; done means users can retrieve relevant logs through a cross-platform `show` or `view` command.

Written by the indexing model from the issue text.