This is needed so that we only write data which was requested
for, using a limit reader avoids spurious reads on the incoming
client data. Additionally using limit reader provides server
safety from rogue clients sending copious amounts of data (for
example a denial of service attack).
This patch also caters for size == -1 when content encoding from
a client is set as chunked, we happily read till io.EOF
AppendFile ensures that it appends the entire buffer. Returns
an error otherwise, this patch removes the necessity for the
caller to look for 'n' return on short writes.
Ref #1893
Strided erasure distribution uses a new randomized
block distribution for each Put operation. This
information is captured inside `xl.json` for subsequent
Get operations.
