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
```
sorry, I am mistaken, simplejson is required in avro_json_serializer.
```
nosetests
E..............................E
======================================================================
ERROR: Failure: ImportError (No module named simplejson.ordered_dict)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/travis/virtualenv/python2.7.8/lib/python2.7/site-packages/nose/loader.py", line 414, in loadTestsFromName
    addr.filename, addr.module)
  File "/home/travis/virtualenv/python2.7.8/lib/python2.7/site-packages/nose/importer.py", line 47, in importFromPath
    return self.importFromDir(dir_path, fqname)
  File "/home/travis/virtualenv/python2.7.8/lib/python2.7/site-packages/nose/importer.py", line 94, in importFromDir
    mod = load_module(part_fqname, fh, filename, desc)
  File "/home/travis/build/OpenBazaar/OpenBazaar/test/test_avroproto.py", line 5, in <module>
    from node.avroproto import avroproto
  File "/home/travis/build/OpenBazaar/OpenBazaar/node/avroproto.py", line 4, in <module>
    from avro_json_serializer import AvroJsonSerializer
  File "/home/travis/virtualenv/python2.7.8/lib/python2.7/site-packages/avro_json_serializer/__init__.py", line 26, in <module>
    from simplejson.ordered_dict import OrderedDict
ImportError: No module named simplejson.ordered_dict
```