Consider adding namespaces to tags

[michaelcfanning]

If we define a separator for tags, we can allow tool producers to serialized a hierarchized set of tags. For example, by using a forward slash, a user could tag a result with multiple CWE designations:

["CWE/973", "CWE/435"]

Similarly, a SARIF converter that transforms Polyspace Verifier output to SARIF might preserve validation-relevant annotations produced by its abstract interpretation engine like so:

"Polyspace/Dead"
"Polyspace/Open"
etc.