"Return" missing from trio_asyncio.run

Closes github #57

Author: smurfix

trio_asyncio/loop.py

@@ -390,4 +390,4 @@ async def _run_task(proc, args):
         async with open_loop(queue_len=queue_len):
             return await proc(*args)
 
-    trio.run(_run_task, proc, args)
+    return trio.run(_run_task, proc, args)