Fixed addressWithIMAPAddress for drafts with bad address in to/cc/bcc fields
Recognize multipart/signed content type
Added extra parameters to attachment
Merge remote-tracking branch 'upstream/master'

Conflicts:
	src/objc/abstract/MCOAbstractPart.h
Merge pull request #815 from miximka/master

Add possibility to recognize multipart/signed messages
Renamed 'extra parameters' of MCAttachment to 'content type parameters'
Merge pull request #814 from foxinushka/feature/attachment-extra-parameters

Added extra parameters to attachment
Merge pull request #805 from foxinushka/master

Fixed addressWithIMAPAddress for drafts with bad address in to/cc/bcc fields