Add BranchesHelper

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/helpers/branches_helper.rb

+module BranchesHelper
+  def can_remove_branch?(project, branch_name)
+     if project.protected_branch? branch_name
+       false
+     elsif branch_name == project.repository.root_ref
+       false
+     else
+       can?(current_user, :push_code, project)
+     end
+  end
+end