rework suite implementation/handling; add DefaultSuite

[kellyredding]

This reworks the suite object to make it more flexible to extend. This follows the pattern of the view object where the base suite provides the core logic/behavior and the default suite provides the default assert behavior. The goal here is to enable extending the suite for use in AssertSqlite (and Parassert).

The suite is responsible for accumulating tests for the runner to run and for providing the run data and test result data. The default suite stores run data and results in memory.

Note: this begins the work of formalizing the test/result data api. In a coming effort, I'll rework the default view to fully use this api and implement the full api in the default suite.

There are a few other smaller changes here:

• I broke out the context info class into its own top-level object. This is purely an organizational change as it has nothing to do with the suite object.
• I simplified how the setups/teardowns are added and accessed. This removes the unecessary complexity of the previous implementation.
• I added a callback setup similar to that of the view. The goal here is to allow custom suites to inject special behavior during test runs (much like the views can). This is just to make suites as extendable as possible and provide the same flexibility as the views.

@jcredding ready for review.

[jcredding]

@kellyredding - Just one question about a few methods that didn't get overridden in the DefaultSuite. Otherwise I'm good with this :boom:

[kellyredding]

@jcredding I'm going to go ahead and merge since your comment will be addressed in a coming effort.