add ReadStream
add read with length in test-read_stream
add WriteStream
fix a bug in write_stream where offset were not updated
get rid of nextTick recursive calls; also remove chunkSize option
move tape from tests/modules to modules/ and add devDependencies in package.lua
added init.lua; fixed a syntax issue in package.lua
add read_large test for ReadStream, trigerring multiple fs.read

also changed small_chunk to write_large for WriteStream test because
chunk_size was removed from WriteOptions
use self:on('open', ...) instead of nextTick() in destroy()
Merge pull request #1 from virgo-agent-toolkit/songgao/wip

Work in Progress