Added unsubscribe_contact method to Mailjet::List. Mailjet::ApiError updated to handle error message in case unsubscribe_contact fails.
Mailjet::Reporting test case for reportGeoip updated since api call is supposed to return an array (https://eu.mailjet.com/docs/api/report/geoip)
In Mailjet::Campaign test the sleeping time for waiting the campaign to be sent has been relaxed to avoid test failing due to delay issues.
Merge pull request #7 from mimmovele/unsubscribe-contact-contributing

Unsubscribe contact contributing