adding integration tests for sending emails with attachment and a body.

related to https://wso2.org/jira/browse/WSAS-1544
and wso2-dev/wso2-axis2@0193ee10f91b67e0a7f3ebcc5dddc27f96a6de8c wso2-dev/wso2-axis2@0193ee10f91b67e0a7f3ebcc5dddc27f96a6de8c