Updating GitLab Mattermost to v3.2 for GitLab 8.10 release

Opening a ticket for the update of GitLab Mattermost to v3.2 in GitLab omnibus.

• Mattermost v3.2 release will be July 17 from http://www.mattermost.org/download/
• Mattermost v3.2-RC2 is available now for download and testing at https://gitlab.mattermost.com/community

Key updates for GitLab Mattermost v3.2

• German language support
• Custom Emoji
• Performance improvements with gzip compression

Full release notes can be found here

Here are optional settings to add to gitlab.rb for GitLab 8.10

If you're replacing the binary file manually (instead of uncompressing the tar.gz) the localization string files en.json, es.json, fr.json, ja.json and pt-BR.json in the /i18n and /web/static/i18n directories would need to be updated from the tar.gz and de.json added for new German support.

Please let me or @it33 know if you have any questions? Thanks!