We need to handle -32700 "Parse error" correctly

[TigerND]

Servers that don't support JSON-RPC 2.0 return a single error "Parse error" (single response but not list of responses).

{u'id': None, u'result': None, u'error': {u'message': u'Parse error', u'code': -32700}}

This situation should be handled correctly.

PS: Tested using Namecoin wallet 0.3.80