Release: SEnginx v1.6.1

Changes:

    *) Feature: upgrade to original nginx 1.7.4.

    *) Change: Replace current syslog support with nginx's original
               one.

    *) Bugfix: Issue #20 on github, a segmentation fault in dynamic
               resolve functionality.

Signed-off-by: Paul Yang(InfoHunter) <paulyang.inf@gmail.com>