Currently `xl.json` saves algorithm information for bit-rot
verification. Since the bit-rot algo's can change in the
future make sure the erasureReadFile doesn't default to
a particular algo. Instead use the checkSumInfo.
* XL/erasure-read: optimize memory allocation during erasure-read by using temporary buffer pool.
With the change the buffer needed during GetObject by erasureReadFile is allocated only once.
* unit-tests: Unit tests for erasureCreateFile and erasureReadFile.
* appendFile() should return errXLWriteQuorum.
* TestErasureReadFileOffsetLength() tests erasureReadFile() for different offset and lengths.
* Fix for the failure seen in the erasure read unit test case. Issue #2227
* Move common erasure setup code to newErasureTestSetup()
* Review fixes. Add few more test cases for erasureReadFile.
* XL: Refactor of xl.PutObjectPart and erasureCreateFile.
* GetCheckSum and AddCheckSum methods for xlMetaV1
* Simple unit test case for erasureCreateFile()
Krishna Srinivas