refactor: introduce new signature method.

ITestCommand ConvertToTestCommand(IMethodInfo, Func<MethodInfo, ITestFixture>)
refactor: remove the old signature

ITestCommand ConvertToTestCommand(IMethodInfo, ITestFixture)
dev: address the code analysis warning

CA2208: Instantiate argument exceptions correctly
dev: address passing correct MethodInfo

First class test should pass MethodInfo of the test delegate to
fixture factory, not MethodInfo of a test method adorned with
FirstClassTheoremAttribute.
style: remove unnecessary type declaration.
refactor: remove the unnecessary test

CreateTestCommandsInitializesTestFixtureForEachTestCase
Merge pull request #29 from jwChung/change-signature

Create only necessary test fixture