message: Fix keytypes name
  Revert change in currency.abi (amount->quantity)
diff: @@ -268,16 +268,16 @@ struct AbiGenerator {
  if( table.indextype == "i64i64i64" && isi64i64i64(fields) ) {
  table.keynames = vector<eos::types::FieldName>{fields[0].name, fields[1].name, fields[2].name};
  - table.keytype = vector<eos::types::TypeName>{fields[0].type, fields[1].type, fields[2].type};
  + table.keytypes = vector<eos::types::TypeName>{fields[0].type, fields[1].type, fields[2].type};
  } else if( table.indextype == "i128i128" && isi128i128(fields) ) {
  table.keynames = vector<eos::types::FieldName>{fields[0].name, fields[1].name};
  - table.keytype = vector<eos::types::TypeName>{fields[0].type, fields[1].type};
  + table.keytypes = vector<eos::types::TypeName>{fields[0].type, fields[1].type};
  } else if( table.indextype == "i64" && isi64(fields) ) {
  table.keynames = vector<eos::types::FieldName>{fields[0].name};
  - table.keytype = vector<eos::types::TypeName>{fields[0].type};
  + table.keytypes = vector<eos::types::TypeName>{fields[0].type};
  } else if( table.indextype == "str" && isstr(fields) ) {
  table.keynames = vector<eos::types::FieldName>{fields[0].name};
  - table.keytype = vector<eos::types::TypeName>{fields[0].type};
  + table.keytypes = vector<eos::types::TypeName>{fields[0].type};
  } else {
  FC_ASSERT(false, "Unable to guess key names");
  }
  