ensure we rollback incase of any exception since we are using transaction.commit_manually, ensures we do not encounter "Transaction managed block ended with pending COMMIT/ROLLBACK"
pep8 cleanup
Delete instances in mongodb directly via a query, ensures that
deletions are faster and hence resolves #993
Merge branch 'master' into 993_faster_xform_delete

* master:
  update test to use instance id on delete
  display only photo attachments on photo view
  ensure mimetype is set on saving an attachment
  pep8
  FIxed tesst to use id param for delete_data url instead of mongo api style queries
  Updated delete data to use the instance id instead of the uuid which can be ducplicated - fixes #927
dropbox chooser added/fixes issue #1012
use file name to check if file exists, fixes #1032
Added doublick click listener in slick grid subclass - Fixes #1033
Merge pull request #1036 from modilabs/1033_double_click_data_view_broken

Added doublick click listener in slick grid subclass - closes #1033
Merge pull request #1031 from modilabs/993_faster_xform_delete

#993 faster xform delete
test for line break
fix for line break
update xml
missing import
fix test fixture
pep8 cleanup
Merge pull request #1039 from modilabs/line-break-fix

Line break fix - closes #1037
Merge pull request #1034 from modilabs/media_hash_fix

use file name to check if file exists, closes #1032
Merge pull request #1040 from modilabs/attachment-missing-import

missing import
Added a default value for CELER_ALWYAS_EAGER to query for async exports
Added support for group delimeter and multi select splitting export options