v0.2.0: Group Support

This release moves away from having a single set of SMS and HTTP configuration to allowing a dynamic number of services.

This release also allows "groups" to be defined so that users can specify which services they should be sent to. Messages can be tagged with a one or more groups, and each group can have one or more endpoints associated with it. This way users can send military or defensive alerts to their alliance without spamming them with messages about local economic conditions.