keybase-installer and strict umask

I have my umask set to 077. Running keybase-installer installs the tools with this umask so only root can use the tools, while running keybase-installer with umask 022 enables the tools for all users on the system.

Perhaps warn about this, or just use umask 022 to install?

Start at the keybase-installer entry point and reproduce the installation with umask 077 and 022; the issue names no source file or test. Confirm how installed tool permissions are determined, then resolve whether done means warning about restrictive permissions or installing with umask 022 and add coverage for that behavior.

Written by the indexing model from the issue text.