Updated ngx_http_lua_module to 0.9.12 version

* The `lua_ssl_trusted_certificate` directive does not work currently.
  It requires at least nginx 1.7.0. Tengine supports nginx 1.6.2 currently.
* Some test cases in modules/ngx_http_lua_module/t cannot pass because these
  cases are customized for nginx. But it does not affect the functionality.
  (Later commit will add more details about test cases to document.)
* move this module from src/http/modules/lua to modules/ngx_http_lua_module