Updating server dependancies. Also adding github.com/jaytaylor/html2text and gopkg.in/gomail.v2 (#5748)

vendor/github.com/miekg/dns/reverse.go

@@ -6,10 +6,10 @@ var StringToType = reverseInt16(TypeToString)
 // StringToClass is the reverse of ClassToString, needed for string parsing.
 var StringToClass = reverseInt16(ClassToString)
 
-// Map of opcodes strings.
+// StringToOpcode is a map of opcodes to strings.
 var StringToOpcode = reverseInt(OpcodeToString)
 
-// Map of rcodes strings.
+// StringToRcode is a map of rcodes to strings.
 var StringToRcode = reverseInt(RcodeToString)
 
 // Reverse a map