[evolution-patches] fix for #310953 (camel-groupwise)

["Jain Vivek" <jvivek novell com>]

hi,

The attached patch fixes 
http://bugzilla.gnome.org/show_bug.cgi?id=310953

patch is attached on the bug.

server doesn't return the contentType for some attachments, we have to
check it and if there is no contentType we set it as multipart/digest.

Thanks,
Vivek Jain