getmail ignores --verbosity command line option

[ptav]

getmail management command always output all logger messages to stdout (including INFO). Creates a potential issue with confidentiality as email details are printed to logs which are retained by the servers.

Ideally verbosity should work as:
0 - Silent, no logger output
1 - Errors and Warnings only
2 - INFO messages and above
3 - DEBUG messages and above

[ptav]

Added pull request #300, awaiting approval