Closing write stream @ movefile() & appendToStream()

After successfully moving the file write stream were not closed. In the first occasion though nodejs automatically close it after finish reading from source; in the second function it opened the write stream even after completely appending the buffer from chunk files. Which might cause the nodejs app to crash if file somehow moved.
Closing write stream ( destStream.end() )

Closing it in 2 more places.
Merge pull request #25 from mdrmuhaimin/master

Closing file write stream and file append stream after the completion of writing in the file.