Print loaded plugin version number and sha

[rickmak]

Followup on #56

[cheungpat]

I understand that @rickmak would like to print loaded plugin version and commit SHA so to make it easy for developer to know which version of the plugins they are running and to help support. How do you think this will be implemented?

Version information is usually stored in setup.py, which means it is usually not available in package code, unless the version number is set in a variable in the package.