Expose packed stream with Unpacker.read_bytes()

At present, Unpacker buffers reading from the stream, meaning the stream can no longer be read directly. Unpacker.read_bytes(n) provides access to the underlying data, allowing content of known size to be read without unpacking.
Cleaner read_bytes and a test case

No longer reads via buffer for unbuffered bytes
Merge commit 'd5f9995' into read_bytes

Conflicts:
	msgpack/_msgpack.pyx
Add changelog
Merge pull request #33 from jnothman/readme-updates

Readme updates
Add Unpacker.read_bytes().

It reads from inner buffer without unpacking.

Merge remote-tracking branch 'jnothman/patch-2'

Conflicts:
	msgpack/_msgpack.pyx
Merge branch 'master' of github.com:msgpack/msgpack-python
Add note about use_list.
Fix README re default use_list=True
Warn about StopIteration in README
Merge pull request #36 from jnothman/patch-3

Warn about StopIteration in README
Merge pull request #35 from jnothman/patch-1

Fix README re default use_list=True
Add NOTE for changing default value of use_list.