Added mime type for MS Outlook application

Added content type ‘application/vnd.ms-outlook’ for the application MS
Outlook with the file extension ‘.msg’. This is not registered in IANA
but found the content type at
http://www.digitalpreservation.gov/formats/fdd/fdd000379.shtml.

Made changes to avoid failure on travis

Reverted back the changes
Finalizing mime-types 2.4 release.