smtp: add the class to verify the certificate of the SMTP server for SMTPS Original "smtplib.SMTP_SSL" has no route to pass "ca_certs" and "cert_reqs" arguments to underlying SSL socket creation. This causes that "getpeercert()" on SSL socket returns empty dict, so the peer certificate for SMTPS can't be verified. This patch introduces the "SMTPS" class derived from "smtplib.SMTP" to pass "ca_certs" and "cert_reqs" arguments to underlying SSL socket creation. "SMTPS" class is derived directly from "smtplib.SMTP", because amount of "smtplib.SMTP_SSL" definition derived from "smtplib.SMTP" is as same as one needed to override it. This patch defines "SMTPS" class, only when "smtplib.SMTP" class has "_get_socket()" method, because this makes using SSL socket instead of normal socket easy. "smtplib.SMTP" class of Python 2.5.x or earlier doesn't have this method. Omitting SMTPS support for them is reasonable, because "smtplib.SMTP_SSL" is already unavailable for them before this patch. Almost all code of "SMTPS" class is imported from "smtplib.SMTP_SSL" of Python 2.7.3, but it differs from original code in point below: - "ssl.wrap_socket()" is replaced by "sslutil.ssl_wrap_socket()" for compatibility between Python versions