Preserve the exact file size given by the client.

Rather than using strip() which deletes all trailing newlines in the file,
just truncate the received buffer to exactly the number of bytes specified by
the client, ensuring that files which originally did not end with a newline
continue not to have a newline, but files which ended with one or more still
have the same number. This fixes issue #11.
Merge pull request #14 from tornewuff/trailing_newlines

Preserve the exact file size given by the client.