security threat model exercise

The threat model is created using OWASP ThreatDragon (https://github.com/OWASP/threat-dragon)
OWASP ThreatDragon is a public domain utility for generating threat model & it is OWASP incubator project.
Other tools can also be used to generate threat model.

threat_model_1.json: Has the threat model defined in json notation
threat_model_1.pdf: Has the threat model report generated from the threat model