Add support for git lfs.

.gitignore

app/controllers/projects_controller.rb

app/models/lfs_object.rb

app/models/lfs_objects_project.rb

app/models/project.rb

app/uploaders/lfs_object_uploader.rb

config/gitlab.yml.example

config/initializers/1_settings.rb

config/routes.rb

db/migrate/20151103134857_create_lfs_objects.rb

db/migrate/20151103134958_create_lfs_objects_projects.rb

db/migrate/20151104105513_add_file_to_lfs_objects.rb

db/migrate/20151114113410_add_index_for_lfs_oid_and_size.rb

db/schema.rb

lib/gitlab/backend/grack_auth.rb

lib/gitlab/git_access.rb

lib/gitlab/lfs/response.rb

lib/gitlab/lfs/router.rb

lib/support/nginx/gitlab

lib/support/nginx/gitlab-ssl