Start updating documentation for V2 API

Move the web API documentation into the 'webapi'
subdirectory to avoid conflicts with the auto-generated
'api' directory contents. Create a v2 doc file
as a placeholder until the automatic documentation
features of WSME are more complete.

blueprint api-server-pecan-wsme

Change-Id: Ide11ad0b4cebb29318b8bb977bc5165334e22a2c
Signed-off-by: Doug Hellmann <doug.hellmann@dreamhost.com>

ceilometer/api/controllers/v2.py

@@ -486,6 +486,11 @@ class Source(Base):
     name = text
     data = {text: text}
 
+    @staticmethod
+    def sample():
+        return Source(name='openstack',
+                      data={'key': 'value'})
+
 
 class SourceController(RestController):
     """Works on resources."""