OR-557 add module for attachments
OR-557 store attachments when saving email message
OR-557 refactor message models
OR-557 change attachmentModule#stroeAttachment signature
OR-557 WIP: promises
OR-557 fix bug: define _id field of attachment
OR-557 code cleaning
OR-557 add unit test for mail attachments parsing
OR-557 add midway test for mail attachments
OR-557 refactor Whastup schema to use base-message and therefore share properties with all other messages
OR-557 remove useless file field from the attachment model
OR-557 store the attachment file name as a metadata in the file store
OR-557 code simplification
Merge pull request #424 in OR/rse from OR/rse-gcrosmarie:OR-557-generic-system-to-handle-attachments-to-ESN-Messages to master

* commit 'b9523f1fec0b13c678fafdd0ac15999c19ea9975':
  OR-557 code simplification
  OR-557 store the attachment file name as a metadata in the file store
  OR-557 remove useless file field from the attachment model
  OR-557 refactor Whastup schema to use base-message and therefore share properties with all other messages
  OR-557 add midway test for mail attachments
  OR-557 add unit test for mail attachments parsing
  OR-557 code cleaning
  OR-557 fix bug: define _id field of attachment
  OR-557 WIP: promises
  OR-557 change attachmentModule#stroeAttachment signature
  OR-557 refactor message models
  OR-557 store attachments when saving email message
  OR-557 add module for attachments