INTEXT-58 Support smpp sending using other character set and udh

* support sending with other character set. e.g. Chinese, Arabic
* support sending long message using UDHI (still need user intervention to compose the UDH).
* support sending long message using message_payload optional parameter (simply by adding a header)
* allow adding 'request-handler-advice-chain'
* allow modifying request timeout on session
* allow to reconnect SMPP connection by wrapping SMPPSession with proxy

See: https://jira.springsource.org/browse/INTEXT-58