Add CLI for error logs
Add CLI for error logs

This adds `augur logging errors [ |all|WORKER]` command, which outputs
only error logs. It can output augur and houskeeper logs, as well as all
worker logs, or only a specific worker log with
`augur logging errors WORKER`

Signed-off-by: Ivana Yovcheva <86e73595f14df5226ef437d57671288872a8681c@vmware.com>

OSSHealth/ghdata,OSSHealth/ghdata,OSSHealth/ghdata