* Enable running PEP8 checks via flake8 as part of the build if flake8 is installed.
Update scripts in \tools and \onnxruntime\python. Excluding \onnxruntime\python\tools which needs a lot more work to be PEP8 compliant. Also excluding orttraining\tools for the same reason.
Install flake8 as part of the static_analysis build task in the Win-CPU CI so the checks are run in one CI build.
Update coding standards doc.
* Update version number to 0.5.0 in preparation for release
* Update to README.md to direct to Versioning doc
* Resolve PR comment
* Remove incorrect line generation
* Minor updates to update version script
* Minor comment update
* unify version logic
* merge function to build.py
* read file to get version
* fix path issue
* format python
* use path join
* fix __init__.py
* move function to a separate file
* remove redundant
