use logging module in client instead of print

[houqp]

Verta python client should use the builtin logging module to handle various info/debug/error logging needs. This way downstream application can have full control over stdout. Using print for logging in a library is generally an anti-pattern in python.

[convoliution]

Thanks @houqp! It's on our radar to replace the print-based "logging" statements with proper logging invocation. I'll make sure to tag this Issue in the PR when it's in.