Vendor update for aws sdk

Updated to latest version of go aws sdk.
Use vendored sub pakages within aws sdk.
Adds missing vendor packages for letsencrypt

Fixes #1832

Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)

vendor/github.com/aws/aws-sdk-go/private/protocol/rest/build.go

@@ -222,8 +222,7 @@ func EscapePath(path string, encodeSep bool) string {
 		if noEscape[c] || (c == '/' && !encodeSep) {
 			buf.WriteByte(c)
 		} else {
-			buf.WriteByte('%')
-			buf.WriteString(strings.ToUpper(strconv.FormatUint(uint64(c), 16)))
+			fmt.Fprintf(&buf, "%%%02X", c)
 		}
 	}
 	return buf.String()