Move to the mattermost/go-i18n fork (#10669)

This change is being made to address an issue where the go-i18n
translation library would result in partial-translations when a
given language dictionary was missing a given plural keyword. The
improvement made here leads the translation library to try an
'other' keyword lookup if the first plural keyword fails to have
a value.

This change was not accepted upstream due to concern regarding
changing the behavior, so we are using a fork at this time to
address the issue.

vendor/modules.txt

@@ -122,6 +122,11 @@ github.com/mailru/easyjson
 github.com/mailru/easyjson/jlexer
 github.com/mailru/easyjson/jwriter
 github.com/mailru/easyjson/buffer
+# github.com/mattermost/go-i18n v1.1.2
+github.com/mattermost/go-i18n/i18n
+github.com/mattermost/go-i18n/i18n/bundle
+github.com/mattermost/go-i18n/i18n/language
+github.com/mattermost/go-i18n/i18n/translation
 # github.com/mattermost/gorp v2.0.1-0.20190301154413-3b31e9a39d05+incompatible
 github.com/mattermost/gorp
 # github.com/mattermost/rsc v0.0.0-20160330161541-bbaefb05eaa0
@@ -157,18 +162,13 @@ github.com/muesli/smartcrop/nfnt
 github.com/muesli/smartcrop/options
 # github.com/nfnt/resize v0.0.0-20180221191011-83c6a9932646
 github.com/nfnt/resize
-# github.com/nicksnyder/go-i18n v1.10.0
-github.com/nicksnyder/go-i18n/i18n
-github.com/nicksnyder/go-i18n/i18n/bundle
-github.com/nicksnyder/go-i18n/i18n/language
-github.com/nicksnyder/go-i18n/i18n/translation
 # github.com/oklog/run v1.0.0
 github.com/oklog/run
 # github.com/olekukonko/tablewriter v0.0.1
 github.com/olekukonko/tablewriter
 # github.com/pborman/uuid v1.2.0
 github.com/pborman/uuid
-# github.com/pelletier/go-toml v1.2.0
+# github.com/pelletier/go-toml v1.3.0
 github.com/pelletier/go-toml
 # github.com/pkg/errors v0.8.1
 github.com/pkg/errors
@@ -220,8 +220,8 @@ github.com/ssor/bom
 github.com/stretchr/objx
 # github.com/stretchr/testify v1.3.0
 github.com/stretchr/testify/require
-github.com/stretchr/testify/mock
 github.com/stretchr/testify/assert
+github.com/stretchr/testify/mock
 github.com/stretchr/testify/suite
 # github.com/throttled/throttled v2.2.4+incompatible
 github.com/throttled/throttled