UpdatePipeline tests (with EF6 comparison)

Removing previous 'PocoCUD' tests that were ported from EF6 test suite
Replacing with UpdatePipeline tests that better represent recommended coding patterns
Adding EF6 equivalent of the new tests (for comparison)
Introduce ability in core framework to control which part of test is measured

I've favored 'writing code like a real app' rather than trying to factor things for a lot of code/database re-use. 

Some rough results from my laptop:

Test | EF6 | EF7
------------ | ------------- | -------------
Insert 1000 entities | 2381 ms | 524 ms
Update 1000 entities | 348 ms | 261 ms
Delete 1000 entities | 3670 ms | 151 ms
Mixed 1000 entities | 2854 ms | 364 ms

I haven't dug too much into the numbers yet, I suspect most of the big differences are batching in EF7. The comparison still seems appropriate though since this is the out-of-the-box perf you get for the same code/scenario.

Obviously we can add more tests to isolate particular parts of the stack to compare. These tests are designed to hit simple high level scenarios.
When we spoke before, we discussed the idea of putting EF6 in the metric name rather than the test name for the sake of comparison.  We can add the ability to add custom labels to the performance metrics now and remove the label from the test name, or we can keep it this way for now, and modify the data in the database once we make this update.