ENYO-1891: do not crash when no PGB token or user is defined

Enyo-DCO-1.1-Signed-off-by: Francois-Xavier KOWALSKI <francois-xavier.kowalski@hp.com>
ENYO-1891: do not crash when no PGB token or user is defined (2)

- Do not try to JSON-parse an empty/undefined answer

Enyo-DCO-1.1-Signed-off-by: Francois-Xavier KOWALSKI <francois-xavier.kowalski@hp.com>
Merge pull request #2 from enyojs/ENYO-1891

ENYO-1891: do not crash when no PGB token or user is defined