Unit Test memory cleanup

This is a first pass at fixing #4185. @jasonsanjose 

I updated all tests that use `SpecRunnerUtils.createTestWindowAndRun()` and tried to release all references to the test window and anything inside it so it will get released on call to `SpecRunnerUtils.closeTestWindow()`

On my Window 7 system, when running Integration Tests this reduces memory ~90M (~11%).
On Mac OSX 10.8 MBP Retina, Integration Tests only, reduces memory ~50M.

We should do a similar analysis of the other `SpecRunnerUtils` methods:

```
createMockDocument()
createMockActiveDocument()
createMockElement()
createMockEditorForDocument()
createMockEditor()
loadProjectInTestWindow()
openProjectFiles()
createTextFile()
```