Delegate deployment username from config. Update Travis notification.
Check module installation using module checking, other minor fixes.

Change to use Ansible's register for module checking instead of
relying on presence of fb2_create_board script. As an additional
benefits, now database is also setup as part of the provisioning
process.

Also change PostgreSQL to reload its configuration files immediately
instead of waiting until the end of play to avoid any possible error
while migrating database (due to configuration file not reloaded.)