Design Test Helpers 2.0

[abilson]

With more use, we've identified some ways to improve Test Helpers to be more intuitive.

• Extract app configuration to allow injection of additional config options.
• Expand IHelper classes to include all: AgentHelper, EHHelper, etc.
• Organize object helpers into a DI factory method and simplify the interfaces

[dvbarnes]

I also would like this, currently we try to remove the hard dependency from the TestHelper class in our helper functions this allows us to add wrappers or other extra goodness that are specific to our business logic but now used in all Helper functions.