* Integration test for activity page

* Small code refactoring for acitvity page

* Move activity stats calculation logic to model

* Fix so that user can still fork his own repository to his organizations

* Fix to only use owned organizations

* Add integration test for forking own repository to owned organization

* Helper functions for intergration test boilerplate

Set request headers in helper functions, and new helper for requests with string-formatted URLs

* Make branch deletion URL more like GitHub's, fixes #1397

* Add PR branch deletion integration test

* Do not allow deleting protected branch

* Change http error code to 403 if user has no write rights to repository

* Add check to not panic if forked repository has alrady been deleted

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>