Print-out account username
Print-out account username

This should reduce @_@ by showing which account the user is currently
on.

kennethlimcp/particle-cli,spark/particle-cli,kennethlimcp/particle-cli,spark/particle-cli,spark/particle-cli,kennethlimcp/particle-cli,kennethlimcp/particle-cli,spark/particle-cli,spark/particle-cli,kennethlimcp/particle-cli,kennethlimcp/particle-cli,spark/particle-cli