v0.15.0

Module `schedule` @Benbentwo (#28)

what

• Add a TF schedule module

why

• The terraform schedule module will be used to create and manage on-call schedules

references

• https://support.atlassian.com/opsgenie/docs/manage-on-call-schedules-and-rotations/
• https://www.atlassian.com/software/opsgenie/on-call-management-and-escalations
• https://support.atlassian.com/opsgenie/docs/build-an-on-call-schedule/