analyzerjs should produce timestamp in ISO format

[sarfata]

Timestamps are parsed and printed as numbers but the original analyzer would convert them to ISOString before printing them.

Example:

echo '$PCDIN,01FD02,00000003,01,00DF00C603FAFFFF*20' |~/work/canboat/rel/darwin-x86_64/analyzer -json
{"timestamp":"1969-12-31-16:00:00,3","prio":0,"src":1,"dst":255,"pgn":130306,"description":"Wind Data","fields":{"SID":0,"Wind Speed":2.23,"Wind Angle":5.5,"Reference":"Apparent"}}

And with CanboatJS:

echo '$PCDIN,01FD02,00000003,01,00DF00C603FAFFFF*20' |~/work/canboatjs/bin/analyzerjs
{"pgn":130306,"timestamp":3,"src":1,"dst":255,"prio":0,"fields":{"SID":0,"Wind Speed":2.23,"Wind Angle":0.0966,"Reference":"Apparent"},"description":"Wind Data"}

PR incoming...