Add ProfileFNamePredicate

Adds a `ProfileFNamePredicate` that returns `true` if a given request is in the context of the profile with the configured `fname`, and `false` otherwise.

See also JIRA [UP-4260](https://issues.jasig.org/browse/UP-4260) and context on [what MyUW is using this Predicate for](http://apetro.ghost.io/pipelines-need-valves/) in conditioning branching of the rendering pipeline.

Intended to be useful as a `Predicate` to plug into a `BranchingRenderingPipeline` to make that branching decision.