encyclopediaWindow: handle no time stamp in FIRST_LAUNCH
encyclopediaWindow: handle no time stamp in FIRST_LAUNCH

Seems like we should be consistent with window.js here.
[endlessm/eos-sdk#3864]

endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib