esmpt: port from openembedded.

The esmtp is not longer being maintained since 1.2,
but it's used at many distribution now such as Ubuntu trusty(14.04LTS).

Signed-off-by: Bian Naimeng <biannm@cn.fujitsu.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Joe MacDonald <joe_macdonald@mentor.com>