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.

go.mod

@@ -41,6 +41,7 @@ require (
 	github.com/konsorten/go-windows-terminal-sequences v1.0.2 // indirect
 	github.com/lib/pq v1.0.0
 	github.com/mailru/easyjson v0.0.0-20190312143242-1de009706dbe // indirect
+	github.com/mattermost/go-i18n v1.1.2
 	github.com/mattermost/gorp v2.0.1-0.20190301154413-3b31e9a39d05+incompatible
 	github.com/mattermost/rsc v0.0.0-20160330161541-bbaefb05eaa0
 	github.com/mattermost/viper v1.0.4
@@ -50,12 +51,12 @@ require (
 	github.com/minio/minio-go v6.0.14+incompatible
 	github.com/mitchellh/go-homedir v1.1.0 // indirect
 	github.com/mitchellh/go-testing-interface v1.0.0 // indirect
-	github.com/nicksnyder/go-i18n v1.10.0
 	github.com/olekukonko/tablewriter v0.0.1 // indirect
 	github.com/onsi/ginkgo v1.8.0 // indirect
 	github.com/onsi/gomega v1.5.0 // indirect
 	github.com/pascaldekloe/goe v0.1.0 // indirect
 	github.com/pborman/uuid v1.2.0
+	github.com/pelletier/go-toml v1.3.0 // indirect
 	github.com/pkg/errors v0.8.1
 	github.com/prometheus/client_golang v0.9.3-0.20190127221311-3c4408c8b829
 	github.com/prometheus/client_model v0.0.0-20190129233127-fd36f4220a90 // indirect