Code samples in README.md contain errors

[digitalfuller]

Code for the "Send an SMS" example has two errors:

1. Missing using System.Linq; statement.
2. Missing semicolon on line 31.

Code for the "Send an MMS" has two errors:

1. Missing using System.Linq; statement.
2. Missing SendMessagesResponse result = messages.CreateSendMessages(request); on line 39