support multiple versions emulation (now only 0.16 is supported)

[gdassori]

• implement jsonrpc validators with pycomb
• create the serialization module, organized by emulation versions
• create version-dependant output serializers
• generalize the vo_service input\output
• add in settings.py the emulated version
• automount the serializer with a decorator

Note:
We always save segwit blocks. It MUST be in charge to the serializer to format outputs for the proper version (this is about <= 0.12 emulation, I guess, I don't think is worth to go backward).

[gdassori]

This should be done before UT on the jsonrpc voservice stuff to avoid wasting time testing stuff is going te be deprecated....

[gdassori]

reference issues #40 #41 #42

[gdassori]

withdrawn