Gets rid of the warning messages caused by `tlsmail`:
> # Get rid of warning messages, see http://stackoverflow.com/questions/8783400/warning-already-initialized-constant-after-installing-tlsmail-gem/9117903#9117903
> #/usr/lib64/ruby/gems/1.9.1/gems/tlsmail-0.0.1/lib/net/smtp.rb:806: warning: already initialized constant SMTPSession
> #/usr/lib64/ruby/gems/1.9.1/gems/tlsmail-0.0.1/lib/net/pop.rb:687: warning: already initialized constant POP
> #/usr/lib64/ruby/gems/1.9.1/gems/tlsmail-0.0.1/lib/net/pop.rb:688: warning: already initialized constant POPSession
> #/usr/lib64/ruby/gems/1.9.1/gems/tlsmail-0.0.1/lib/net/pop.rb:689: warning: already initialized constant POP3Session
> #/usr/lib64/ruby/gems/1.9.1/gems/tlsmail-0.0.1/lib/net/pop.rb:702: warning: already initialized constant APOPSession