SPDY 模式支持不完美

一些ngx_lua提供的Lua APIs在Nginx的SPDY模式下确定不能工作：ngx.location.capture](#ngxlocationcapture)， ngx.location.capture_multi，和ngx.req.socket。

English source:

SPDY Mode Not Fully Supported

Certain Lua APIs provided by ngx_lua do not work in Nginx's SPDY mode yet: ngx.location.capture, ngx.location.capture_multi, and ngx.req.socket.