Eliminate .NET 2.0 Agent

[CharliePoole]

Microsoft support of .NET 2.0 ended in July, 2011. We should remove the agent and all 2.0 engine tests and test data.

At the same time, the console runner and engine themselves should be updated to use .NET 4.6.2 rather than 2.0. This is a big change with a lot of detail but should be straight-forward, since all the code compiled for 2.0 runs under 4.x as well..

Essentially all .NET 2.0 builds will be removed and all conditional statements referencing .NET 2.0 removed from the code.