Problem: acceptance tests are using old pydriver (#2282)

Solution: update to the new driver version, and simplify the code
removing the `mode` parameter.

acceptance/python/Dockerfile

@@ -5,4 +5,4 @@ RUN pip install --upgrade \
 	pycco \
 	websocket-client~=0.47.0 \
 	pytest~=3.0 \
-	bigchaindb-driver==0.5.0a2
+	bigchaindb-driver==0.5.0a4

acceptance/python/src/test_basic.py

@@ -59,7 +59,7 @@ def test_basic():
 
 
     # Now she is ready to send it to the BigchainDB Network.
-    sent_transfer_tx = bdb.transactions.send(fulfilled_creation_tx, mode='commit')
+    sent_transfer_tx = bdb.transactions.send(fulfilled_creation_tx)
 
     # And just to be 100% sure, she also checks if she can retrieve
     # it from the BigchainDB node.
@@ -106,7 +106,7 @@ def test_basic():
             private_keys=alice.private_key)
 
     # She finally sends the transaction to a BigchainDB node.
-    sent_transfer_tx = bdb.transactions.send(fulfilled_transfer_tx, mode='commit')
+    sent_transfer_tx = bdb.transactions.send(fulfilled_transfer_tx)
 
     # And just to be 100% sure, she also checks if she can retrieve
     # it from the BigchainDB node.

acceptance/python/src/test_double_spend.py

@@ -26,7 +26,7 @@ def test_double_create():
 
     def send_and_queue(tx):
         try:
-            bdb.transactions.send(tx, mode='commit')
+            bdb.transactions.send(tx)
             results.put('OK')
         except bigchaindb_driver.exceptions.TransportError as e:
             results.put('FAIL')