Add an option to skip the Mattermost server version check (#849)

Adds SkipVersionCheck bool option for mattermost

bridge/config/config.go

@@ -127,6 +127,7 @@ type Protocol struct {
 	ShowUserTyping         bool       // slack
 	ShowEmbeds             bool       // discord
 	SkipTLSVerify          bool       // IRC, mattermost
+	SkipVersionCheck       bool       // mattermost
 	StripNick              bool       // all protocols
 	SyncTopic              bool       // slack
 	TengoModifyMessage     string     // general

bridge/mattermost/helpers.go

@@ -70,6 +70,7 @@ func (b *Bmattermost) apiLogin() error {
 		b.mc.SetLogLevel("debug")
 	}
 	b.mc.SkipTLSVerify = b.GetBool("SkipTLSVerify")
+	b.mc.SkipVersionCheck = b.GetBool("SkipVersionCheck")
 	b.mc.NoTLS = b.GetBool("NoTLS")
 	b.Log.Infof("Connecting %s (team: %s) on %s", b.GetString("Login"), b.GetString("Team"), b.GetString("Server"))
 	err := b.mc.Login()