Pull request batch2: Batch of my different pull requests

Following pull requests are grouped in this PR:
https://github.com/s3tools/s3cmd/pull/342
https://github.com/s3tools/s3cmd/pull/357
https://github.com/s3tools/s3cmd/pull/416

This PR is based on "Pull Request batch1" so also include:
https://github.com/s3tools/s3cmd/pull/369
https://github.com/s3tools/s3cmd/pull/348
https://github.com/s3tools/s3cmd/pull/355  ( Bugfix import error)
https://github.com/s3tools/s3cmd/pull/385