* Refactored code, updated comments and documentation related to TF OD API models pre-processing.
* Improved MO messages related to pre-processor block removal during conversion of the TD OD API models. Remove mean/scale if padding is used and mean/scale is applied before resize
* Updated TF OD API transformation and documentation for SSD models
* Updated comments and documentation for the ObjectDetectionAPIMaskRCNNSigmoidReplacement transformation
* Updated comments and documentation for the ObjectDetectionAPIMaskRCNNROIPoolingSecondReplacement transformation
* Updated comments and documentation for the ObjectDetectionAPIPSROIPoolingReplacement transformation
* Updated comments and documentation for the ObjectDetectionAPIProposalReplacement transformation
* Updated comments and documentation for the ObjectDetectionAPIDetectionOutputReplacement transformation
* Minor code style fixes
* Fixed unit tests for ObjectDetectionAPIPreprocessor2Replacement transformation
* Improved unit test for pipeline.config parser. Fixed very long bug with incorrect test data for the PipelineConfig parser class
* Code style fixes
* Get rid of "coordinates_swap_method" parameter in the JSON configuration file for TF OD API models
* Code style fixes and minor refactoring
* Simplied code related to swapping Proposal coordinates
* Removed incorrectly removed code
* Fixed code review comments about the code comments