add jz.zip.ZipArchiveWriter

• add jz.zip.ZipArchiveWriter
• small fixes

jz.zip.ZipArchiveWriter usage:

 var writer = new jz.zip.ZipArchiveWriter({shareMemory: true, chunkSize: 0xf000});
 writer
 .on('data', function(chunk) {
   // chunk is Uint8Array.
 })
 .on('end', function() {
   // ...
 });
 .write('foo/bar/baz.txt', buffer)
 .write('a.mp3', mp3Buff)
 .writeEnd();

v2.4.0

Features:

• use asm.js
• use ES6-Promises
• add stream APIs

Fix:

• rename ZipArchiveReader#getFileAsFoo -> ZipAchiveReader#readFileAsFoo
• rename jz.utils.concatByteArrays -> jz.utils.concatBytes
• almost APIs return or set an argument to the then callback as Uint8Array