Fix i18n messages in novaclient, part II

This change make all the text visible by the user i18n. The
messages changes are in prints, logs, exceptions, helps, etc
Pep8 errors about "Multiple positional placeholders" also fixed.

Change-Id: Ia69c86bb2ee8be3fa8af734f793a81eefebe362d
Merge "Fix i18n messages in novaclient, part II"