Merge pull request #24 from technorama/master

add symbolize_keys support to unpack (compatible with msgpack-jruby)
default rake task executes :spec and :doc as well as :build
added documents for :symbolized_keys
fixed options parameter handling
updated spec for symbolize_keys
updated documents
fixed error message
fixed compatibility with MRI 1.8
v0.5.8
added msgpack.org.md
updated msgpack.org.md
updated msgpack.org.md
Merge remote-tracking branch 'upstream/master'

Conflicts:
	ext/msgpack/buffer.h
	ext/msgpack/buffer_class.c