[WIP] add avro schema to support other languages

Add [Apache Avro](http://avro.apache.org/) protocol schema for other [Supported Languages](https://cwiki.apache.org/confluence/display/AVRO/Supported+Languages).It was only a partial modification to the attempt. Not centain if such avro schema can fit this project.

```
$ nosetests test/test_avroproto.py
....
----------------------------------------------------------------------
Ran 4 tests in 0.002s

OK
```
The new [version](https://github.com/linkedin/python-avro-json-serializer/pull/1) of `avro_json_serializer` has been pushed to PyPI. Can you try it out and see if it works without `simplejson`?