Merge pull request #452 from Kapishin/master

Fix typos
pluginized the socket protocols
completed --https-socket
force https to on when --https-socket is in place
added tests/websockets_chat.pl
fixed comments in websockets_chat.pl
fixed no default app
fixed default app usage
another fix for default app
fixed stupid bug in websocket perl example
added oid metric in stats
added avg metrics collector
added support for proxy protocol
added uwsgi over SSL
fixed master hang when gracefully reloading in lazy mode
Merge pull request #454 from xiaost-bytedance/master

fixed master hang when gracefully reloading in lazy mode
added --plshell and Perl uwsgi::rpc
added chunked input api to psgi
prepare for 1.9.20