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
```
@y12studio: The upstream PR is [ready](https://github.com/linkedin/python-avro-json-serializer/pull/1). I will remove the `simplejson` requirement once they merge me, so the present PR can go through, as far as I am concerned.