[EM] Added adapter for Cloudmailin email service.
Fixed a typo in the test and fixed the code to make it pass. Cloudmailin doesn't pass attachments at all if there aren't any so I decided it should be an empty array in this case.
Merge pull request #37 from r38y/cloudmailin-typo

Fixed a typo in the test and fixed the code to make it pass. Cloudmailin...
Fresh hash from CloudmailinAdapter

Return a new hash with only the neccessary keys from the Cloudmailin
adapter.
[#33] Parsed headers support

Uses Mail gem to parse optional headers in the params hash.
Document expected adapter normalized_params
Add status badges to README
Added a Postmark adapter
Merge pull request #38 from r38y/postmark

Adapter for the Postmark Parse API
Merge remote-tracking branch 'origin/pr/34'

Conflicts:
  README.md
Increase minor version for new release of 0.4.0