py/modio: resource_stream: Implement "package" param handling.

tests/io/resource_stream.py

@@ -7,10 +7,8 @@ except AttributeError:
     print('SKIP')
     sys.exit()
 
-try:
-    buf = uio.resource_stream("data", "file2")
-except NotImplementedError:
-    pass
+buf = uio.resource_stream("data", "file2")
+print(buf.read())
 
 # resource_stream(None, ...) look ups from current dir, hence sys.path[0] hack
 buf = uio.resource_stream(None, sys.path[0] + "/data/file2")

tests/io/resource_stream.py.exp

@@ -1 +1,2 @@
 1234
+1234