Add ordering sequence to params in query (#73)

* Add ordering sequence to params

Makes possible to add ordering sequence to Query. Fixes #72

Signed-off-by: Rafik Naccache <rafik@fekr.tech>

* Add :param ordering_sequence:

Signed-off-by: Rafik Naccache <rafik@fekr.tech>

* Fix wrong example for :param ordering_sequence:

Signed-off-by: Rafik Naccache <rafik@fekr.tech>

* fix wrong ordering message construction in query

After more documentation I got to the way to construct to ordering object

Signed-off-by: Rafik Naccache <rafik@fekr.tech>

* remove redundant OR clause to manage ordering_sequence

Signed-off-by: Rafik Naccache <rafik@fekr.tech>

iroha/iroha.py

@@ -244,7 +244,7 @@ def command(name, **kwargs):
         return command_wrapper
 
     def query(self, name, counter=1, creator_account=None,
-              created_time=None, page_size=None, first_tx_hash=None,
+              created_time=None, page_size=None, first_tx_hash=None, ordering_sequence=None,
               **kwargs):
         """
         Creates a protobuf query with specified set of entities
@@ -254,6 +254,8 @@ def query(self, name, counter=1, creator_account=None,
         :param created_time: query creation timestamp in milliseconds
         :param page_size: a non-zero positive number, size of result rowset for queries with pagination
         :param first_tx_hash: optional hash of a transaction that will be the beginning of the next page
+        :param ordering_sequence: an array representing an ordering spec, containing a sequence of fields and directions 
+            example: [[queries_pb2.kCreatedTime, queries_pb2.kAscending],[queries_pb2.kPosition, queries_pb2.kDescending]]
         :param kwargs: query arguments as they defined in schema
         :return: a proto query
         """
@@ -269,6 +271,13 @@ def query(self, name, counter=1, creator_account=None,
             pagination_meta.page_size = page_size
             if first_tx_hash:
                 pagination_meta.first_tx_hash = first_tx_hash
+        if ordering_sequence:
+            ordering = queries_pb2.Ordering()
+            for ordering_elt in ordering_sequence:
+                ordering_field = ordering.sequence.add()
+                ordering_field.field = ordering_elt[0]
+                ordering_field.direction = ordering_elt[1]
+            pagination_meta.ordering.CopyFrom(ordering)
 
         meta = queries_pb2.QueryPayloadMeta()
         meta.created_time = created_time