Refs #8374 HFIRBackgroundAPIv2 no longer leaves files behind

Implemented cleanup in all the tests contained in HFIRBackgroundAPIv2.py, removing all the files it leaves behind.
Refs #8374 HFIRTestsAPIv2 no longer leaves files behind

Implemented cleanup in HFIRTestsAPIv2.py, removing all the files it leaves behind.
Refs #8374 HFIREffAPIv2 no longer leaves files behind

Implemented cleanup in HFIREffAPIv2.py, removing all the files it leaves behind.
Refs #8374 HFIRReductionAPIv2 no longer leaves files behind

Implemented cleanup in HFIRReductionAPIv2.py, removing all the files it leaves behind.
Refs #8374 HFIRTransAPIv2 no longer leaves files behind

Implemented cleanup in HFIRTransAPIv2.py, removing all the files it leaves behind.
Refs #8374 Cleaned up code in HFIRTestsAPIv2 and HFIRBackgroundAPIv2

HFIRTestsAPIv2.py and HFIRBackgroundAPIv2.py have had their cleanup code imporved to follow better python practice and reduce repeated code.
Refs #8374 EQSANS Tests no longer leave files behind

EQSANSTransAPIv2.py, EQSANSBeamCurrentAPIv2.py, EQSANSDarkCurrentAPIv2.py, EQSANSEffAPIv2.py, EQSANSIQOutputAPIv2.py, EQSANSProcessedEffAPIv2.py and EQSANSSolidAPIv2.py have had cleanup implemented, removing all the files they leave behind.
Refs #8374 SNSPowderRedux no longer leaves files behind

Implemented cleanup in SNSPowderRedux.py, removing all the files it leaves behind.
Refs #8374 LOQAddBatch no longer leaves files behind

Implemented cleanup in LOQAddBatch.py, removing all the files it leaves behind.
Refs #8374 Diffraction_Workflow_Test no longer leaves files behind

Implemented cleanup in Diffraction_Workflow_Test.py, removing all the files it leaves behind.
Refs #8374 Added fix for CalibrateRectangularDetector_Test

Russell told me about a test that I'd missed, but as it only runs on Red Hat 6 I wouldn't have seen it.

He supplied a fix which i've added to the appropriate places.
Merge remote branch 'origin/feature/8374_clean_up_tests'