Use "AreEqual" instead of "IsTrue" to display specific double value

Currently the following test cases fail with one error message: ```Expected: True```. That doesn't quite tell what is the resulting value, only ```True``` or ```False```. This request fixes that by using ```Assert.AreEqual``` (instead of the current ```Assert.IsTrue```) method.

```
Dynamo.Tests.CoreDynTests.AddSubtractMapReduceFilterBasic
Dynamo.Tests.CoreDynTests.Cosine
Dynamo.Tests.CoreDynTests.OrNode
Dynamo.Tests.CoreDynTests.Repeat
Dynamo.Tests.CoreDynTests.Sine
Dynamo.Tests.CoreDynTests.Tangent
Dynamo.Tests.CustomNodes.FilterWithCustomNode
Dynamo.Tests.CustomNodes.MultipleOutputs
Dynamo.Tests.CustomNodes.PartialApplicationWithMultipleOutputs
Dynamo.Tests.DSLibraryTest.TestLibraryAcrossSessions
Dynamo.Tests.ListTests.Combine_ComplexTest
Dynamo.Tests.ListTests.Smooth_InputListNode
Dynamo.Tests.ListTests.Smooth_SimpleTest
Dynamo.Tests.ListTests.Sort_NumbersfFromDiffInput
Dynamo.Tests.ListTests.SortBy_SimpleTest
Dynamo.Tests.UI.CoreUserInterfaceTests.PreferenceSetting
```