teleport start default output

[kontsevoy]

Problem 1

Our quickstart promises this output:

$ mkdir -p /var/lib/teleport
$ sudo teleport start

[AUTH]  Auth service is starting on 0.0.0.0:3025
[PROXY] Reverse tunnel service is starting on 0.0.0.0:3024
[PROXY] Web proxy service is starting on 0.0.0.0:3080
[PROXY] SSH proxy service is starting on 0.0.0.0:3023
[SSH]   Service is starting on 0.0.0.0:3022

Notice the absence of --debug flag.
2.5 is giving this:

WARN [PROCESS]   No TLS Keys provided, using self signed certificate. service/service.go:1474
WARN [AUTH]      Parameter advertise_ip is not set for this auth server. Trying to guess the IP this server can be reached at: 192.168.122.1:3025. service/service.go:684

Problem 2

$ tctl users add ekontsevoy
user "User(name=ekontsevoy, roles=[], identities=[])" already exists

Should be "user ekontsevoy already exists"

Proposal

• When in "zero-configuration mode" (i.e. no YAML config provided) Teleport should start with ERROR log level (so those warnings won't confuse first-timers).
• Default stderr output should be as before.
• Make the warning more readable / less verbose for advertise_ip (Ev: I'll update the text myself)

[klizhentas]

Also provide more progress during migrations of the sessions, to let admins know about what's actually going on.

[kontsevoy]

@klizhentas I've fixed "problem 2", removing myself from assigness.