Logging was calling wrong function name, could have crashed PZH

Jira Issue: WP-1069
Add another piece of configuration data: invitation tokens

These tokens are used when inviting someone to join your personal
zone for the first time, and must be persistent.

Jira issue: WP-1064
Merge pull request #16 from jplyle/support-invite-tokens

Add configuration support for invitation tokens
Merge pull request #17 from habibvirji/master

Correct API call