Fix task for uploading release

Author: yanne

BUILD.rest

@@ -104,7 +104,7 @@ Releasing
   > invoke test
   > invoke version 1.xx
   > invoke register
-  > invoke sdist upload
+  > invoke sdist --upload
   > git commit -am 'Version 1.xx'
   > git tag 1.xx
   > git push --tags

tasks.py

@@ -186,11 +186,11 @@ def release_notes_plugin():
 @task(pre=[clean],
       help={
           'release-notes': 'If enabled, release notes plugin will be updated'})
-def sdist(release_notes=True):
+def sdist(release_notes=True, upload=False):
     """Creates source distribution with bundled dependencies."""
     if release_notes:
         release_notes_plugin()
-    _run_setup('sdist')
+    _run_setup('sdist{}'.format('' if not upload else ' upload'))
     _after_distribution()