add UTF8 test - passes
also use ByteBuffer.readUTF8StringBytes for Node.js,
saves converting to Buffer
see http://htmlpreview.github.io/?http://github.com/dcodeIO/ByteBuffer.js/master/docs/ByteBuffer.html#readUTF8StringBytes
Merge pull request #11 from nrenner/utf8

also use ByteBuffer.readUTF8StringBytes for Node.js