Updating from NUnit 2.6.3 to NUnit 3.5.0

[conniey]

Updates the current test projects to NUnit 3.5.0.

• Replaces obsolete TestFixtureSetUp and TestFixtureTearDown with OneTimeSetUp and OneTimeTearDown
• Replaces [ExpectedException] with Assert.Throws<T>
• Adds a reason for [Ignore] tests because it is required now

Is there anything I need to edit in make it work in TeamCity?

PR #191 depends on this because dotnet-test-nunit uses NUnit 3.5.0

[conniey]

@synhershko @NightOwl888 Is there anything I need to do to get this merged in?

[synhershko]

Looks good to me, but seems like it's blocked by #191?

[conniey]

@synhershko This doesn't depend on #191. I created this PR off of master.

[synhershko]

Ok, cool, merging now

[NightOwl888]

@synhershko

I reverted these commits because we already have this change in #191 and it causes a conflict, not to mention it breaks the build (see #200).

[synhershko]

Cool thanks - that's why I asked before merging...

[conniey]

@synhershko @NightOwl888 When I had opened this PR, no one was working on my branch, so I was going to rebase my commits on top of this so there would be less changes to look at in #191. :) But since there is active development.