NativeTask sort data as bytecomparator

[zoken]

Issue founded by a testcase:
using nativetask to read a sequence file with IntWritable vey and IntWritable value, then write to HDFS.

sample data(sequence file content):
1649017694 409447690
1961194481 389281748
1972912194 -1727627767
-1962537218 1879855206
-424314478 -1772058909
-1622710398 -666322232
-691459978 1444896200
-1275884969 1162424531
-976606073 -1485431141

Nativetask output content:
1649017694 409447690
1928185315 -267386735
1961194481 389281748
1972912194 -1727627767
-1962537218 1879855206
-1622710398 -666322232
-1275884969 1162424531
-976606073 -1485431141
-691459978 1444896200
-424314478 -1772058909

Expected output content:
-1962537218 1879855206
-1622710398 -666322232
-1275884969 1162424531
-976606073 -1485431141
-691459978 1444896200
-424314478 -1772058909
1649017694 409447690
1928185315 -267386735
1961194481 389281748
1972912194 -1727627767

Remark:
In this case, we expect result sorted by int, factually it sorted by byte.

[clockfly]

Implemented