[WIP] Attempt to debug SIGSEGV and SIGABRT signal to worker

[lucernae]

celery worker often crashed because of unknown.

Possible cause at the moment:

• QGIS doesn't cleanly exit after task finished (will try to solve using context manager)
• There is memory leak on QGIS internally (cannot fix)

We need to consistently reproduce the bug so we can track which statement caused this.

[lucernae]

For now, this PR is just to see travis log for various cases.

[lucernae]

Always fails on test run multi exposure with this errors:

2018-11-08 07:42:01,653 - InaSAFE - INFO - ANALYSIS : Styling
QObject::startTimer: QTimer can only be used with threads started with QThread
QPixmap: Must construct a QApplication before a QPaintDevice