buffer: no warning when encoding isn't passed
buffer: no warning when encoding isn't passed

Buffer#write() was showing the deprecation warning when only
buf.write('string') was passed. This is incorrect since the encoding is
always optional.

Argument order should follow:
  Buffer#write(string[, offset[, length]][, encoding])

(yeah, not confusing at all)

dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node