Added ability to list groups in a domain.

Working skeleton of  groups listing method implemented.
Still needs timeout checking, formatting, etc.
Small text cleanup.
DRY'd out login/reauth/timeout process

Moved logic to Login class. Controller handles
GApps session, login and reauth so UserManagement
and GroupManagement classes don't have separate
copies of the session they have to manage.
Timeout checking bug fixed. Small formatting fixes/tweaks.
Merge branch 'refactor_login'

Authentication code DRY'd out.
Modified user table output to four columns.

Increased overall width of application from 80 to 100
chars. User table is now four columns instead of two,
more compact that way.
Merge branch 'format_users_table'

Users table condensed to four columns.