Record an alert

### Description
As a user I want to record a new emergency alert/warning so that I can notify key stakeholders to take mitigation and preparedness actions and tasks
### Screenshots
### References
- [Common Alerting Protocol Version 1.2](http://docs.oasis-open.org/emergency/cap/v1.2/CAP-v1.2-os.pdf)
### Tasks
#### API:
- [ ] I should be able to post an alert to API
- [ ] I should be able to get alert/warn from API
- [ ] I should be able to get alerts/warns from API
- [ ] I should be able to identify related alerts
- [ ] I should be able to perform assessments based on a specific alert
- [ ] I should be able to identify associated incidents based on an alert
- [ ] I should be able to notify stakeholder when issue an alert
- [ ] I should be able to remind stakeholders about an alert after some specified time
- [ ] I should be to activate mitigation and preparedness activities
- [ ] I should be able to disseminate mitigation and preparedness activities to respective stakeholders base on their roles
#### Web UI:
- [ ] I should be able to record an alert
- [ ] I should be able to view a list of alerts
- [ ] I should be able to view an alert
- [ ] I should be able to view assessment(s) based on an alert
- [ ] I should be able to related incident(s) based on an alert
- [ ] I should be able to view alerts related to a particular alert
- [ ] I should be able to view notified stakeholders count by roles
- [ ] I should be able to view disseminated mitigation and preparedness activities based on stakeholder roles
#### Documentation
- [ ] Create minimal alert user guide