bb.fetch: add fetch version to distinguish bb.fetch and bb.fetch2

there is case that we need to distingush bb.fetch and bb.fetch2,
and use different API for bb.fetch and bb.fetch2. so it is necessary
to add version info for distinguish purpose

Signed-off-by: Yu Ke <ke.yu@intel.com>

bitbake/lib/bb/fetch/__init__.py

@@ -33,6 +33,8 @@ from   bb import data
 from   bb import persist_data
 from   bb import utils
 
+__version__ = "1"
+
 logger = logging.getLogger("BitBake.Fetch")
 
 class MalformedUrl(Exception):

bitbake/lib/bb/fetch2/__init__.py

@@ -33,6 +33,8 @@ from   bb import data
 from   bb import persist_data
 from   bb import utils
 
+__version__ = "2"
+
 logger = logging.getLogger("BitBake.Fetch")
 
 class MalformedUrl(Exception):