Use StandardCharset UTF-8

AS I understand it, starting with Java 1.7, all JVM must support the UTF-8 charset. Prior to JDK 7, it was required to do something like:

    try {
      byte[] buf = str.getBytes("UTF-8");
      trans_.write(buf);
    } catch (UnsupportedEncodingException uex) {
      throw new TException("JVM DOES NOT SUPPORT UTF-8");
    }

However, now there is available java.nio.charset.StandardCharsets which provides the required charsets and therefore there is no longer a need to do a try/catch to encode/decode Strings and UTF-8 byte arrays. This will save on lines of code and removes the overhead of the try/catch block.