Add Trackers to Group

Adds trackers to a group, the user must be the group owner.

• user -> login account email
• pwd -> md5 hash of the password
• token -> optional instead of user and pwd
• grpID -> group identifier
• trackers -> json encoded array of trackers to add
• deviceSn -> serial number of the tracker (must be unique)
• trackerID -> (optional) when defined will look up the tracker serial number instead of using deviceSn
• lt24ID -> (optional) when defined will look up the tracker(s) belonging to livetrack24 user instead of using deviceSn
• TrackerName
• gender
• civlID
• compeID -> competition ID, must be unique
• country -> 3 letter ISO country code.
• GliderImg -> glider image identifier.
• spot -> spot tracker ID.
• inreach -> inreach tracker ID.
• phone -> pilot phone number.