Remove user OAuth tokens stored in database for Bitbucket, GitHub, and GitLab

and request them each session. Pass these tokens to the project import data.

This prevents the need to encrypt these tokens and clear them in case they
expire or get revoked.

For example, if you deleted and re-created OAuth2 keys for Bitbucket, you would get
an Error 500 with no way to recover:

```
Started GET "/import/bitbucket/status" for x.x.x.x at 2015-08-07 05:24:10 +0000
Processing by Import::BitbucketController#status as HTML
Completed 500 Internal Server Error in 607ms (ActiveRecord: 2.3ms)

NameError (uninitialized constant Import::BitbucketController::Unauthorized):
  app/controllers/import/bitbucket_controller.rb:77:in `rescue in go_to_bitbucket_for_permissions'
  app/controllers/import/bitbucket_controller.rb:74:in `go_to_bitbucket_for_permissions'
  app/controllers/import/bitbucket_controller.rb:86:in `bitbucket_unauthorized'
```

Closes #1871

1 files changed, 2 insertions, 1 deletions

diff --git a/app/workers/repository_import_worker.rb b/app/workers/repository_import_worker.rb
index b546f8777e1..f2ba2e15e7b 100644
--- a/app/workers/repository_import_worker.rb
+++ b/app/workers/repository_import_worker.rb
@@ -25,9 +25,10 @@ class RepositoryImportWorker
                           end
     return project.import_fail unless data_import_result
 
+    Gitlab::BitbucketImport::KeyDeleter.new(project).execute if project.import_type == 'bitbucket'
+
     project.import_finish
     project.save
     ProjectCacheWorker.perform_async(project.id)
-    Gitlab::BitbucketImport::KeyDeleter.new(project).execute if project.import_type == 'bitbucket'
   end
 end