Timestamped traces

[cdupont]

It would be nice to have timestamped traces, e.g.:

127.0.0.1 - - [01/Jul/2019 12:57:57] "GET /api/v1/system/wifi HTTP/1.1" 201 -

[j-forster]

Ref: 847c512

An env-variable WAZIUP_LOG has been added to support different modes:

WAZIUP_LOG = "mode,mode,..."
modes: date, time, utc, error, warn, verbose, debug

Without any mode:

[MQTT ] MQTT Server at ":1883".
[HTTP ] HTTP Server at ":80". Use "http://".
[WS   ] MQTT via WebSocket Server at ":80". Use "ws://".
[MQTT ] "mosqsub|13996-DESKTOP-L" Connected Protocol 0x4

With date,time,debug:

2019/08/28 13:56:30 [MQTT ] MQTT Server at ":1883".
2019/08/28 13:56:30 [HTTP ] HTTP Server at ":80". Use "http://".
2019/08/28 13:56:30 [WS   ] MQTT via WebSocket Server at ":80". Use "ws://".
2019/08/28 13:56:31 [MQTT ] "mosqsub|13996-DESKTOP-L" > CONNECT (MQTT 4) "mosqsub|13996-DESKTOP-L" cs:true kat:60
2019/08/28 13:56:31 [MQTT ] "mosqsub|13996-DESKTOP-L" Connected Protocol 0x4
2019/08/28 13:56:31 [MQTT ] "mosqsub|13996-DESKTOP-L" < CONNACK code:0 sess:false