ensure mimetype is set on saving an attachment
display only photo attachments on photo view
Merge branch 'master' into photo-display-only

* master: (35 commits)
  Updated csv and xls data urls to match new named url patterns
  Re-enabled nosetests
  pep8 cleanup
  pep8
  pep8 cleanup, raise exceptions
  return a valid OpenRosaResponse for the head request
  async kml export support
  separated kml export data generation into a function of its own
  link to zip export list
  delete zip exports after a specified period
  task to generate attachments zip export
  generate attachments zip export function
  add zip export type and mime
  refactored attachment zip to a utils function
  create zip file from Attachments model
  get full filepath of an attachment
  for large size submissions, ensure attachments are saved, as the submission is treated as a duplicate
  handle ZeroDivisionError exceptions, occurs when the height  and thumbnail height are the same
  Implemented language changes on column picker - fixes #955
  Updated query mongo to enclose query params in an  - fixes #622
  ...

Conflicts:
	odk_logger/models/attachment.py
Merge pull request #1028 from modilabs/photo-display-only

Display image attachments only