export of dynamic sites fails if some sites have no position
querying: https://felyx.cersat.fr/services/csv/?type=dynamic
this fails when some dynamic sites have no position (django error with the following message:
#!bash
Request Method: GET
Request URL: http://felyx.cersat.fr/services/csv/?type=dynamic
Django Version: 1.5.12
Exception Type: Exception
Exception Value:
No positions for site vong14wp
Exception Location: /usr/local/lib/python2.7/dist-packages/felyx_django/apps/services/sitesviews.py in export_sites, line 206