Release: SEnginx v1.5.11

Changes:

    *) Feature: upgrade to original nginx 1.5.11, which fixes
       CVE-2014-0088 security problem.

    *) Feature: global user-agent whitelist, with DNS reverse lookup
       mechanism.

    *) Feature: naxsi module supports global user-agent
       whitelist and ip whitelist.

    *) Feature: cookie poisoning module supports global
       user-agent whitelist and ip whitelist.

    *) Feature: web defacement module supports global
       user-agent whitelist and ip whitelist.

    *) Feature: robot mitigation module supports
       global user-agent whitelist and ip whitelist.

    *) Feature: ngx_cache_purge module is integrated.

    *) Bugfix: solve memory leaks in robot mitigation module.

Signed-off-by: paulyang <y_y@neusoft.com>