added possibility to automatically send a mail to the committer
disable setting send_mail_to_committer by default
validate email address
Merge branch 'notifycommitter' of github.com:tsteur/git-commit-notifier into notifycommitter
Merge pull request #179 from tsteur/notifycommitter

Added possibility to automatically send email commit message to the committer
Simplify email check

Take a note that we have IDN-domains, for example.