Clean up code that is used to create buffers

[deepakjois]

Both index.js and test.js have some ugliness because of the way the code was ported from Go.

Here is an example:

  {
    desc: 'WAV audio #1',
    data: Buffer.concat([
      Buffer.from('RIFFb'),
      Buffer.from([0xb8, 0x00, 0x00]),
      Buffer.from('WAVEfmt '),
      Buffer.from([0x12, 0x00, 0x00, 0x00, 0x06])
    ]),
    contentType: 'audio/wave'
},

The problem is that Go strings with \x?? in them get encoded to bytes differently from Javascript strings with \x?? in them. In Javascript, something like \xff uses 2 bytes in a Buffer, but \x00 takes one byte. As a result, we need to have code like above to make sure Go byte buffers translate to equivalent Javascript byte buffers.

As part of cleanup:

• try and find a better idiom for code written above
• Cleanup all \x00 in Javascript code because it can get confusing. It is not obvious upfront how many bytes does a given hexademical escape sequence take up