report export exceptions to mail-admins
XFormParser is already in odk_viewer/models/xform_parser.py
a little more info for export exceptions
Merge pull request #1151 from modilabs/report_exception_in_zip_exports

Email admins exception in exports
catch HTTP errors thrown by stathat api and report to admins - fixes #1152
Removed ipdb call
Merge branch '1152_stathat_api_http_errors' of github.com:modilabs/formhub into 1152_stathat_api_http_errors