Fixed the free and delete mismatch problem.
https://github.com/msgpack/msgpack-c/issues/52
Removed redundant null check.
Removed a redundant null check.
Merge pull request #61 from redboltz/fix_delete_free_mismatch

Fixed the free and delete mismatch problem.
Merge pull request #62 from redboltz/remove_redundant_null_check

Removed a redundant null check.
Replaced deprecated functions in example/stream.cc