Clean up imports to be pyflakes-checkable. fixes #2450

Signed-off-by: Daira Hopwood <daira@jacaranda.org>

qa/rpc-tests/test_framework/blockstore.py

@@ -3,7 +3,10 @@
 #             and for constructing a getheaders message
 #
 
-from mininode import *
+from mininode import CBlock, CBlockHeader, CBlockLocator, CTransaction, msg_block, msg_headers, msg_tx
+
+import sys
+import cStringIO
 import dbm
 
 class BlockStore(object):