* fix bug: modify '0x1f' to '0x3f' in func strdecode; use strdecode in test
* fix bug: call copyArray only when body is not null
* optimize func Message.decode
* use '<<' to replace 'Math.pow'
* use 'new Buffer' and 'buffer.toString' to replace encode/decode utf8
Merge pull request #5 from palmtoy/master

fix some bugs; optimize some code;