gitlab.com importer: refactorig

app/assets/javascripts/importer_status.js.coffee

app/controllers/import/base_controller.rb

app/controllers/import/github_controller.rb

app/controllers/import/gitlab_controller.rb

app/views/import/base/create.js.haml

app/views/import/github/status.html.haml

app/views/import/gitlab/create.js.haml

app/views/import/gitlab/status.html.haml

app/views/projects/_github_import_modal.html.haml

app/views/projects/_gitlab_import_modal.html.haml

app/views/projects/new.html.haml

app/workers/repository_import_worker.rb

lib/gitlab/github_import/importer.rb

lib/gitlab/gitlab_import/importer.rb