Provide ability to add custom "Played Role" values when adding observables

[cdiraimondi]

Problem to Solve

When adding an observable there is no way to add a custom Played Role value. For example, when adding an email address for someone who was the target of a phishing email, there is no method to add a new Played Role value of Recipient. This same problem would apply for IP Address and Domain.

Current Workaround

None

Proposed Solution

Provide the ability to add custom "Played Role" values in a settings page. Played roles must be entities that are able to be linked to a relation of type "indicates".

Additional Information

Multiple observable types have the idea of directionality such as Email Address, IP Address and Domain.