Feature/issue 90

[Vnajeb]

Fixes #90

Changes proposed in this pull request:

• Consistent logging hierarchy every module now uses logging.getLogger(__ name __), replacing bare print() calls and the misleading websockets.client logger name.
• Connections, pool scaling, and query stages (prepare/execute/fetch/close) log at the appropriate level (INFO/DEBUG/ERROR).
• Credential safe passwords and Kerberos tokens are never logged only host, realm, and error codes appear.

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• If this PR fixes a bug, I've added a test that will fail without my fix.
• If this PR adds a new feature, I've added tests that sufficiently cover my new functionality.