clarify basic configuration example and nginx versions compatibility to close #145 and fix clone url to close #135

Co-Authored by: Roman Kuzmin <romanoza@gmail.com>
Signed-off-by: Wandenberg <wandenberg@gmail.com>

ensure all queue members are initialized to not produce errors on calling remove function, without insert them on a queue

remove global references to main module conf, ping and long polling timeout messages, and shared memory zones

add push_stream_timeout_with_body directive to indicate whether send a full message on timed out long polling connections, or not

start etag as 1 to avoid concurrency problems when subscriber connects on the same second of a message is published

change the publish message action through a WebSocket connection to add the message to all subscribed channels

make possible post messages in some channels or delete them at once specifying their ids on push_stream_channels_path diretive separated by a slash